diff --git a/src/ImageSharp/Advanced/AotCompilerTools.cs b/src/ImageSharp/Advanced/AotCompilerTools.cs
index eae4bb4898..b90a6ce3cd 100644
--- a/src/ImageSharp/Advanced/AotCompilerTools.cs
+++ b/src/ImageSharp/Advanced/AotCompilerTools.cs
@@ -508,16 +508,16 @@ namespace SixLabors.ImageSharp.Advanced
         [Preserve]
         private static void AotCompileDither<TPixel, TDither>()
             where TPixel : unmanaged, IPixel<TPixel>
-            where TDither : class, IDither
+            where TDither : struct, IDither
         {
             var octree = default(OctreeQuantizer<TPixel>);
-            default(TDither).ApplyQuantizationDither<OctreeQuantizer<TPixel>, TPixel>(octree, default, default, default);
+            default(TDither).ApplyQuantizationDither<OctreeQuantizer<TPixel>, TPixel>(ref octree, default, default, default);
 
             var palette = default(PaletteQuantizer<TPixel>);
-            default(TDither).ApplyQuantizationDither<PaletteQuantizer<TPixel>, TPixel>(palette, default, default, default);
+            default(TDither).ApplyQuantizationDither<PaletteQuantizer<TPixel>, TPixel>(ref palette, default, default, default);
 
             var wu = default(WuQuantizer<TPixel>);
-            default(TDither).ApplyQuantizationDither<WuQuantizer<TPixel>, TPixel>(wu, default, default, default);
+            default(TDither).ApplyQuantizationDither<WuQuantizer<TPixel>, TPixel>(ref wu, default, default, default);
             default(TDither).ApplyPaletteDither<PaletteDitherProcessor<TPixel>.DitherProcessor, TPixel>(default, default, default);
         }
 
diff --git a/src/ImageSharp/Processing/Processors/Dithering/ErroDither.KnownTypes.cs b/src/ImageSharp/Processing/Processors/Dithering/ErroDither.KnownTypes.cs
index 90df6c7108..4c01fb4023 100644
--- a/src/ImageSharp/Processing/Processors/Dithering/ErroDither.KnownTypes.cs
+++ b/src/ImageSharp/Processing/Processors/Dithering/ErroDither.KnownTypes.cs
@@ -6,7 +6,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
     /// <summary>
     /// An error diffusion dithering implementation.
     /// </summary>
-    public partial class ErrorDither
+    public readonly partial struct ErrorDither
     {
         /// <summary>
         /// Applies error diffusion based dithering using the Atkinson image dithering algorithm.
diff --git a/src/ImageSharp/Processing/Processors/Dithering/ErrorDither.cs b/src/ImageSharp/Processing/Processors/Dithering/ErrorDither.cs
index 37171a2ed3..27bb660e9e 100644
--- a/src/ImageSharp/Processing/Processors/Dithering/ErrorDither.cs
+++ b/src/ImageSharp/Processing/Processors/Dithering/ErrorDither.cs
@@ -15,7 +15,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
     /// An error diffusion dithering implementation.
     /// <see href="http://www.efg2.com/Lab/Library/ImageProcessing/DHALF.TXT"/>
     /// </summary>
-    public partial class ErrorDither : IDither, IEquatable<ErrorDither>, IEquatable<IDither>
+    public readonly partial struct ErrorDither : IDither, IEquatable<ErrorDither>, IEquatable<IDither>
     {
         private readonly int offset;
         private readonly DenseMatrix<float> matrix;
@@ -91,17 +91,17 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void ApplyQuantizationDither<TFrameQuantizer, TPixel>(
-            TFrameQuantizer quantizer,
+            ref TFrameQuantizer quantizer,
             ImageFrame<TPixel> source,
             IndexedImageFrame<TPixel> destination,
             Rectangle bounds)
-            where TFrameQuantizer : class, IQuantizer<TPixel>
+            where TFrameQuantizer : struct, IQuantizer<TPixel>
             where TPixel : unmanaged, IPixel<TPixel>
         {
-            // if (this == default)
-            // {
-            //     ThrowDefaultInstance();
-            // }
+            if (this == default)
+            {
+                ThrowDefaultInstance();
+            }
 
             int offsetY = bounds.Top;
             int offsetX = bounds.Left;
@@ -131,16 +131,16 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void ApplyPaletteDither<TPaletteDitherImageProcessor, TPixel>(
-            TPaletteDitherImageProcessor processor,
+            in TPaletteDitherImageProcessor processor,
             ImageFrame<TPixel> source,
             Rectangle bounds)
-            where TPaletteDitherImageProcessor : class, IPaletteDitherImageProcessor<TPixel>
+            where TPaletteDitherImageProcessor : struct, IPaletteDitherImageProcessor<TPixel>
             where TPixel : unmanaged, IPixel<TPixel>
         {
-            // if (this == default)
-            // {
-            //     ThrowDefaultInstance();
-            // }
+            if (this == default)
+            {
+                ThrowDefaultInstance();
+            }
 
             Buffer2D<TPixel> sourceBuffer = source.PixelBuffer;
             float scale = processor.DitherScale;
diff --git a/src/ImageSharp/Processing/Processors/Dithering/IDither.cs b/src/ImageSharp/Processing/Processors/Dithering/IDither.cs
index 24846db307..1b046c7bc7 100644
--- a/src/ImageSharp/Processing/Processors/Dithering/IDither.cs
+++ b/src/ImageSharp/Processing/Processors/Dithering/IDither.cs
@@ -22,11 +22,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
         /// <param name="destination">The destination quantized frame.</param>
         /// <param name="bounds">The region of interest bounds.</param>
         void ApplyQuantizationDither<TFrameQuantizer, TPixel>(
-            TFrameQuantizer quantizer,
+            ref TFrameQuantizer quantizer,
             ImageFrame<TPixel> source,
             IndexedImageFrame<TPixel> destination,
             Rectangle bounds)
-            where TFrameQuantizer : class, IQuantizer<TPixel>
+            where TFrameQuantizer : struct, IQuantizer<TPixel>
             where TPixel : unmanaged, IPixel<TPixel>;
 
         /// <summary>
@@ -39,10 +39,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
         /// <param name="source">The source image.</param>
         /// <param name="bounds">The region of interest bounds.</param>
         void ApplyPaletteDither<TPaletteDitherImageProcessor, TPixel>(
-            TPaletteDitherImageProcessor processor,
+            in TPaletteDitherImageProcessor processor,
             ImageFrame<TPixel> source,
             Rectangle bounds)
-            where TPaletteDitherImageProcessor : class, IPaletteDitherImageProcessor<TPixel>
+            where TPaletteDitherImageProcessor : struct, IPaletteDitherImageProcessor<TPixel>
             where TPixel : unmanaged, IPixel<TPixel>;
     }
 }
diff --git a/src/ImageSharp/Processing/Processors/Dithering/OrderedDither.KnownTypes.cs b/src/ImageSharp/Processing/Processors/Dithering/OrderedDither.KnownTypes.cs
index a89b239f30..1934604522 100644
--- a/src/ImageSharp/Processing/Processors/Dithering/OrderedDither.KnownTypes.cs
+++ b/src/ImageSharp/Processing/Processors/Dithering/OrderedDither.KnownTypes.cs
@@ -6,7 +6,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
     /// <content>
     /// An ordered dithering matrix with equal sides of arbitrary length
     /// </content>
-    public partial class OrderedDither
+    public readonly partial struct OrderedDither
     {
         /// <summary>
         /// Applies order dithering using the 2x2 Bayer dithering matrix.
diff --git a/src/ImageSharp/Processing/Processors/Dithering/OrderedDither.cs b/src/ImageSharp/Processing/Processors/Dithering/OrderedDither.cs
index 6338bc5b3c..da0a852b8c 100644
--- a/src/ImageSharp/Processing/Processors/Dithering/OrderedDither.cs
+++ b/src/ImageSharp/Processing/Processors/Dithering/OrderedDither.cs
@@ -12,7 +12,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
     /// <summary>
     /// An ordered dithering matrix with equal sides of arbitrary length
     /// </summary>
-    public partial class OrderedDither : IDither, IEquatable<OrderedDither>, IEquatable<IDither>
+    public readonly partial struct OrderedDither : IDither, IEquatable<OrderedDither>, IEquatable<IDither>
     {
         private readonly DenseMatrix<float> thresholdMatrix;
         private readonly int modulusX;
@@ -105,17 +105,17 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void ApplyQuantizationDither<TFrameQuantizer, TPixel>(
-            TFrameQuantizer quantizer,
+            ref TFrameQuantizer quantizer,
             ImageFrame<TPixel> source,
             IndexedImageFrame<TPixel> destination,
             Rectangle bounds)
-            where TFrameQuantizer : class, IQuantizer<TPixel>
+            where TFrameQuantizer : struct, IQuantizer<TPixel>
             where TPixel : unmanaged, IPixel<TPixel>
         {
-            // if (this == default)
-            // {
-            //     ThrowDefaultInstance();
-            // }
+            if (this == default)
+            {
+                ThrowDefaultInstance();
+            }
 
             int spread = CalculatePaletteSpread(destination.Palette.Length);
             float scale = quantizer.Options.DitherScale;
@@ -134,24 +134,19 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
             }
         }
 
-        // public void ApplyQuantizationDither<TFrameQuantizer, TPixel>(TFrameQuantizer quantizer, ImageFrame<TPixel> source,
-        //     IndexedImageFrame<TPixel> destination, Rectangle bounds)
-        //     where TFrameQuantizer : class, IQuantizer<TPixel> where TPixel : unmanaged, IPixel<TPixel> =>
-        //     throw new NotImplementedException();
-
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void ApplyPaletteDither<TPaletteDitherImageProcessor, TPixel>(
-            TPaletteDitherImageProcessor processor,
+            in TPaletteDitherImageProcessor processor,
             ImageFrame<TPixel> source,
             Rectangle bounds)
-            where TPaletteDitherImageProcessor : class, IPaletteDitherImageProcessor<TPixel>
+            where TPaletteDitherImageProcessor : struct, IPaletteDitherImageProcessor<TPixel>
             where TPixel : unmanaged, IPixel<TPixel>
         {
-            // if (this == default)
-            // {
-            //     ThrowDefaultInstance();
-            // }
+            if (this == default)
+            {
+                ThrowDefaultInstance();
+            }
 
             int spread = CalculatePaletteSpread(processor.Palette.Length);
             float scale = processor.DitherScale;
diff --git a/src/ImageSharp/Processing/Processors/Dithering/PaletteDitherProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Dithering/PaletteDitherProcessor{TPixel}.cs
index 3b02a965d2..07af8a5af0 100644
--- a/src/ImageSharp/Processing/Processors/Dithering/PaletteDitherProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Dithering/PaletteDitherProcessor{TPixel}.cs
@@ -47,7 +47,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
         protected override void OnFrameApply(ImageFrame<TPixel> source)
         {
             var interest = Rectangle.Intersect(this.SourceRectangle, source.Bounds());
-            this.dither.ApplyPaletteDither(this.ditherProcessor, source, interest);
+            this.dither.ApplyPaletteDither(in this.ditherProcessor, source, interest);
         }
 
         /// <inheritdoc/>
@@ -74,7 +74,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
         /// <see cref="IPaletteDitherImageProcessor{TPixel}.GetPaletteColor(TPixel)"/>.
         /// </summary>
         /// <remarks>Internal for AOT</remarks>
-        internal class DitherProcessor : IPaletteDitherImageProcessor<TPixel>, IDisposable
+        internal readonly struct DitherProcessor : IPaletteDitherImageProcessor<TPixel>, IDisposable
         {
             private readonly EuclideanPixelMap<TPixel> pixelMap;
 
diff --git a/src/ImageSharp/Processing/Processors/Quantization/EuclideanPixelMap{TPixel}.cs b/src/ImageSharp/Processing/Processors/Quantization/EuclideanPixelMap{TPixel}.cs
index 071bd4643a..b82ce71bbd 100644
--- a/src/ImageSharp/Processing/Processors/Quantization/EuclideanPixelMap{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Quantization/EuclideanPixelMap{TPixel}.cs
@@ -22,7 +22,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
         where TPixel : unmanaged, IPixel<TPixel>
     {
         private Rgba32[] rgbaPalette;
-        private ColorDistanceCache cache;
+        private readonly ColorDistanceCache cache;
         private readonly Configuration configuration;
 
         /// <summary>
@@ -136,13 +136,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
             return (deltaR * deltaR) + (deltaG * deltaG) + (deltaB * deltaB) + (deltaA * deltaA);
         }
 
-        public void Dispose()
-        {
-            this.cache.Dispose();
-            GC.SuppressFinalize(this);
-        }
-
-        ~EuclideanPixelMap() => throw new Exception("very bad");
+        public void Dispose() => this.cache.Dispose();
 
         /// <summary>
         /// A cache for storing color distance matching results.
@@ -155,7 +149,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
         /// Entry count is currently limited to 1185921 entries (2371842 bytes ~2.26MB).
         /// </para>
         /// </remarks>
-        private class ColorDistanceCache : IDisposable
+        private unsafe struct ColorDistanceCache : IDisposable
         {
             private const int IndexBits = 5;
             private const int IndexAlphaBits = 5;
@@ -164,18 +158,16 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
             private const int RgbShift = 8 - IndexBits;
             private const int AlphaShift = 8 - IndexAlphaBits;
             private const int Entries = IndexCount * IndexCount * IndexCount * IndexAlphaCount;
-            // private MemoryHandle tableHandle;
+            private MemoryHandle tableHandle;
             private readonly IMemoryOwner<short> table;
-            // private readonly short* tablePointer;
-            private Memory<short> tableMemory;
+            private readonly short* tablePointer;
 
             public ColorDistanceCache(MemoryAllocator allocator)
             {
                 this.table = allocator.Allocate<short>(Entries);
                 this.table.GetSpan().Fill(-1);
-                this.tableMemory = this.table.Memory;
-                // this.tableHandle = this.table.Memory.Pin();
-                // this.tablePointer = (short*)this.tableHandle.Pointer;
+                this.tableHandle = this.table.Memory.Pin();
+                this.tablePointer = (short*)this.tableHandle.Pointer;
             }
 
             [MethodImpl(InliningOptions.ShortMethod)]
@@ -186,8 +178,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
                 int b = rgba.B >> RgbShift;
                 int a = rgba.A >> AlphaShift;
                 int idx = GetPaletteIndex(r, g, b, a);
-                // this.tablePointer[idx] = index;
-                this.table.Memory.Span[idx] = index;
+                this.tablePointer[idx] = index;
             }
 
             [MethodImpl(InliningOptions.ShortMethod)]
@@ -198,8 +189,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
                 int b = rgba.B >> RgbShift;
                 int a = rgba.A >> AlphaShift;
                 int idx = GetPaletteIndex(r, g, b, a);
-                // match = this.tablePointer[idx];
-                match = this.tableMemory.Span[idx];
+                match = this.tablePointer[idx];
                 return match > -1;
             }
 
@@ -224,15 +214,9 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
             {
                 if (this.table != null)
                 {
-                    // this.tableHandle.Dispose();
+                    this.tableHandle.Dispose();
                     this.table.Dispose();
                 }
-                GC.SuppressFinalize(this);
-            }
-
-            ~ColorDistanceCache()
-            {
-                throw new Exception("very bad");
             }
         }
     }
diff --git a/src/ImageSharp/Processing/Processors/Quantization/OctreeQuantizer{TPixel}.cs b/src/ImageSharp/Processing/Processors/Quantization/OctreeQuantizer{TPixel}.cs
index 99a41a3c87..e28de54c25 100644
--- a/src/ImageSharp/Processing/Processors/Quantization/OctreeQuantizer{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Quantization/OctreeQuantizer{TPixel}.cs
@@ -5,7 +5,6 @@ using System;
 using System.Buffers;
 using System.Numerics;
 using System.Runtime.CompilerServices;
-using System.Runtime.ConstrainedExecution;
 using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
@@ -17,7 +16,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
     /// <see href="http://msdn.microsoft.com/en-us/library/aa479306.aspx"/>
     /// </summary>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
-    public class OctreeQuantizer<TPixel> : IQuantizer<TPixel>
+    public struct OctreeQuantizer<TPixel> : IQuantizer<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         private readonly int maxColors;
@@ -53,11 +52,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
             this.isDisposed = false;
         }
 
-        ~OctreeQuantizer()
-        {
-            throw new Exception("Very bad");
-        }
-
         /// <inheritdoc/>
         public Configuration Configuration { get; }
 
@@ -132,12 +126,12 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
 
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
-        public IndexedImageFrame<TPixel> QuantizeFrame(ImageFrame<TPixel> source, Rectangle bounds)
-            => QuantizerUtilities.QuantizeFrame(this, source, bounds);
+        public readonly IndexedImageFrame<TPixel> QuantizeFrame(ImageFrame<TPixel> source, Rectangle bounds)
+            => QuantizerUtilities.QuantizeFrame(ref Unsafe.AsRef(this), source, bounds);
 
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
-        public byte GetQuantizedColor(TPixel color, out TPixel match)
+        public readonly byte GetQuantizedColor(TPixel color, out TPixel match)
         {
             // Octree only maps the RGB component of a color
             // so cannot tell the difference between a fully transparent
@@ -164,8 +158,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
                 this.pixelMap?.Dispose();
                 this.pixelMap = null;
             }
-
-            GC.SuppressFinalize(this);
         }
 
         /// <summary>
diff --git a/src/ImageSharp/Processing/Processors/Quantization/PaletteQuantizer{TPixel}.cs b/src/ImageSharp/Processing/Processors/Quantization/PaletteQuantizer{TPixel}.cs
index 1a338d5700..284f4fa701 100644
--- a/src/ImageSharp/Processing/Processors/Quantization/PaletteQuantizer{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Quantization/PaletteQuantizer{TPixel}.cs
@@ -3,7 +3,6 @@
 
 using System;
 using System.Runtime.CompilerServices;
-using System.Runtime.ConstrainedExecution;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -14,7 +13,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
     /// <see href="http://msdn.microsoft.com/en-us/library/aa479306.aspx"/>
     /// </summary>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
-    internal class PaletteQuantizer<TPixel> : IQuantizer<TPixel>
+    internal struct PaletteQuantizer<TPixel> : IQuantizer<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         private EuclideanPixelMap<TPixel> pixelMap;
@@ -36,8 +35,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
             this.pixelMap = new EuclideanPixelMap<TPixel>(configuration, palette);
         }
 
-        ~PaletteQuantizer() => throw new Exception("Very bad");
-
         /// <inheritdoc/>
         public Configuration Configuration { get; }
 
@@ -49,8 +46,8 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
 
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
-        public IndexedImageFrame<TPixel> QuantizeFrame(ImageFrame<TPixel> source, Rectangle bounds)
-            => QuantizerUtilities.QuantizeFrame(this, source, bounds);
+        public readonly IndexedImageFrame<TPixel> QuantizeFrame(ImageFrame<TPixel> source, Rectangle bounds)
+            => QuantizerUtilities.QuantizeFrame(ref Unsafe.AsRef(this), source, bounds);
 
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
@@ -60,7 +57,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
 
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
-        public byte GetQuantizedColor(TPixel color, out TPixel match)
+        public readonly byte GetQuantizedColor(TPixel color, out TPixel match)
             => (byte)this.pixelMap.GetClosestColor(color, out match);
 
         /// <inheritdoc/>
@@ -68,7 +65,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
         {
             this.pixelMap?.Dispose();
             this.pixelMap = null;
-            GC.SuppressFinalize(this);
         }
     }
 }
diff --git a/src/ImageSharp/Processing/Processors/Quantization/QuantizerUtilities.cs b/src/ImageSharp/Processing/Processors/Quantization/QuantizerUtilities.cs
index c70f2079a8..5aa79d732e 100644
--- a/src/ImageSharp/Processing/Processors/Quantization/QuantizerUtilities.cs
+++ b/src/ImageSharp/Processing/Processors/Quantization/QuantizerUtilities.cs
@@ -71,10 +71,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
         /// A <see cref="IndexedImageFrame{TPixel}"/> representing a quantized version of the source frame pixels.
         /// </returns>
         public static IndexedImageFrame<TPixel> QuantizeFrame<TFrameQuantizer, TPixel>(
-            TFrameQuantizer quantizer,
+            ref TFrameQuantizer quantizer,
             ImageFrame<TPixel> source,
             Rectangle bounds)
-            where TFrameQuantizer : class, IQuantizer<TPixel>
+            where TFrameQuantizer : struct, IQuantizer<TPixel>
             where TPixel : unmanaged, IPixel<TPixel>
         {
             Guard.NotNull(source, nameof(source));
@@ -88,13 +88,13 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
 
             if (quantizer.Options.Dither is null)
             {
-                SecondPass(quantizer, source, destination, interest);
+                SecondPass(ref quantizer, source, destination, interest);
             }
             else
             {
                 // We clone the image as we don't want to alter the original via error diffusion based dithering.
                 using ImageFrame<TPixel> clone = source.Clone();
-                SecondPass(quantizer, clone, destination, interest);
+                SecondPass(ref quantizer, clone, destination, interest);
             }
 
             return destination;
@@ -114,11 +114,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
 
         [MethodImpl(InliningOptions.ShortMethod)]
         private static void SecondPass<TFrameQuantizer, TPixel>(
-            TFrameQuantizer quantizer,
+            ref TFrameQuantizer quantizer,
             ImageFrame<TPixel> source,
             IndexedImageFrame<TPixel> destination,
             Rectangle bounds)
-            where TFrameQuantizer : class, IQuantizer<TPixel>
+            where TFrameQuantizer : struct, IQuantizer<TPixel>
             where TPixel : unmanaged, IPixel<TPixel>
         {
             IDither dither = quantizer.Options.Dither;
@@ -136,14 +136,14 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
 
                     for (int x = bounds.Left; x < bounds.Right; x++)
                     {
-                        destinationRow[x - offsetX] = quantizer.GetQuantizedColor(sourceRow[x], out TPixel _);
+                        destinationRow[x - offsetX] = Unsafe.AsRef(quantizer).GetQuantizedColor(sourceRow[x], out TPixel _);
                     }
                 }
 
                 return;
             }
 
-            dither.ApplyQuantizationDither(quantizer, source, destination, bounds);
+            dither.ApplyQuantizationDither(ref quantizer, source, destination, bounds);
         }
     }
 }
diff --git a/src/ImageSharp/Processing/Processors/Quantization/WuQuantizer{TPixel}.cs b/src/ImageSharp/Processing/Processors/Quantization/WuQuantizer{TPixel}.cs
index e7b6b74e35..cc53299528 100644
--- a/src/ImageSharp/Processing/Processors/Quantization/WuQuantizer{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Quantization/WuQuantizer{TPixel}.cs
@@ -5,7 +5,6 @@ using System;
 using System.Buffers;
 using System.Numerics;
 using System.Runtime.CompilerServices;
-using System.Runtime.ConstrainedExecution;
 using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
@@ -32,7 +31,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
     /// </para>
     /// </remarks>
     /// <typeparam name="TPixel">The pixel format.</typeparam>
-    internal class WuQuantizer<TPixel> : IQuantizer<TPixel>
+    internal struct WuQuantizer<TPixel> : IQuantizer<TPixel>
         where TPixel : unmanaged, IPixel<TPixel>
     {
         private readonly MemoryAllocator memoryAllocator;
@@ -101,8 +100,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
             this.isDithering = this.isDithering = !(this.Options.Dither is null);
         }
 
-        ~WuQuantizer() => throw new Exception("very bad");
-
         /// <inheritdoc/>
         public Configuration Configuration { get; }
 
@@ -165,11 +162,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
 
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
-        public IndexedImageFrame<TPixel> QuantizeFrame(ImageFrame<TPixel> source, Rectangle bounds)
-            => QuantizerUtilities.QuantizeFrame(this, source, bounds);
+        public readonly IndexedImageFrame<TPixel> QuantizeFrame(ImageFrame<TPixel> source, Rectangle bounds)
+            => QuantizerUtilities.QuantizeFrame(ref Unsafe.AsRef(this), source, bounds);
 
         /// <inheritdoc/>
-        public byte GetQuantizedColor(TPixel color, out TPixel match)
+        public readonly byte GetQuantizedColor(TPixel color, out TPixel match)
         {
             if (this.isDithering)
             {
@@ -206,8 +203,6 @@ namespace SixLabors.ImageSharp.Processing.Processors.Quantization
                 this.pixelMap?.Dispose();
                 this.pixelMap = null;
             }
-
-            GC.SuppressFinalize(this);
         }
 
         /// <summary>