diff --git a/common/build.gradle.kts b/common/build.gradle.kts
index 4dfd7ef1ad..bec5c8bdf6 100644
--- a/common/build.gradle.kts
+++ b/common/build.gradle.kts
@@ -50,8 +50,8 @@ dependencies {
         }
     })
 
-    compileOnly("io.github.llamalad7:mixinextras-common:0.3.5")
-    annotationProcessor("io.github.llamalad7:mixinextras-common:0.3.5")
+    compileOnly("io.github.llamalad7:mixinextras-common:0.4.1")
+    annotationProcessor("io.github.llamalad7:mixinextras-common:0.4.1")
 
     compileOnly("net.fabricmc:sponge-mixin:0.13.2+mixin.0.8.5")
     compileOnly("net.fabricmc:fabric-loader:${BuildConfig.FABRIC_LOADER_VERSION}")
diff --git a/common/src/main/java/net/caffeinemc/mods/sodium/client/data/config/MixinConfig.java b/common/src/main/java/net/caffeinemc/mods/sodium/client/data/config/MixinConfig.java
index c4434f2105..d3e2d3447a 100644
--- a/common/src/main/java/net/caffeinemc/mods/sodium/client/data/config/MixinConfig.java
+++ b/common/src/main/java/net/caffeinemc/mods/sodium/client/data/config/MixinConfig.java
@@ -63,6 +63,7 @@ protected MixinConfig() {
 
         this.addMixinRule("features.render.immediate", true);
         this.addMixinRule("features.render.immediate.buffer_builder", true);
+        this.addMixinRule("features.render.immediate.buffer_upload", true);
         this.addMixinRule("features.render.immediate.matrix_stack", true);
 
         this.addMixinRule("features.render.model", true);
diff --git a/common/src/main/java/net/caffeinemc/mods/sodium/mixin/features/render/immediate/buffer_upload/GlBufferAccessor.java b/common/src/main/java/net/caffeinemc/mods/sodium/mixin/features/render/immediate/buffer_upload/GlBufferAccessor.java
new file mode 100644
index 0000000000..8354a82ee7
--- /dev/null
+++ b/common/src/main/java/net/caffeinemc/mods/sodium/mixin/features/render/immediate/buffer_upload/GlBufferAccessor.java
@@ -0,0 +1,12 @@
+package net.caffeinemc.mods.sodium.mixin.features.render.immediate.buffer_upload;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Accessor;
+import com.mojang.blaze3d.opengl.GlBuffer;
+
+@Mixin(GlBuffer.class)
+public interface GlBufferAccessor {
+
+    @Accessor
+    void setInitialized(boolean value);
+}
diff --git a/common/src/main/java/net/caffeinemc/mods/sodium/mixin/features/render/immediate/buffer_upload/VertexFormatMixin.java b/common/src/main/java/net/caffeinemc/mods/sodium/mixin/features/render/immediate/buffer_upload/VertexFormatMixin.java
new file mode 100644
index 0000000000..37ebba8b1a
--- /dev/null
+++ b/common/src/main/java/net/caffeinemc/mods/sodium/mixin/features/render/immediate/buffer_upload/VertexFormatMixin.java
@@ -0,0 +1,34 @@
+package net.caffeinemc.mods.sodium.mixin.features.render.immediate.buffer_upload;
+
+import java.nio.ByteBuffer;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+import com.llamalad7.mixinextras.injector.ModifyReceiver;
+import com.llamalad7.mixinextras.sugar.Cancellable;
+import com.llamalad7.mixinextras.sugar.Local;
+import com.mojang.blaze3d.buffers.GpuBuffer;
+import com.mojang.blaze3d.systems.CommandEncoder;
+import com.mojang.blaze3d.vertex.VertexFormat;
+
+/**
+ * Fixes an issue where buffer uploads can be slow on some systems due to Vanilla using {@code glBufferSubData} in 1.21.5 (MC-295893).
+ */
+@Mixin(VertexFormat.class)
+public class VertexFormatMixin {
+
+    @ModifyReceiver(method = { "uploadImmediateVertexBuffer", "uploadImmediateIndexBuffer" }, at = @At(value = "INVOKE", target = "Lcom/mojang/blaze3d/buffers/GpuBuffer;size()I"), require = 2)
+    private GpuBuffer replaceBufferData(GpuBuffer gpuBuffer, ByteBuffer data, @Local CommandEncoder commandEncoder, @Cancellable CallbackInfoReturnable<GpuBuffer> cir) {
+        //Setting the initialized field to false forces the glBufferSubData path to be skipped in GlCommandEncoder
+        ((GlBufferAccessor) gpuBuffer).setInitialized(false);
+        //Update the size of the GpuBuffer
+        gpuBuffer.size = data.remaining();
+
+        //Write the data and cancel the method
+        commandEncoder.writeToBuffer(gpuBuffer, data, 0);
+        cir.setReturnValue(gpuBuffer);
+
+        return gpuBuffer;
+    }
+}
diff --git a/common/src/main/resources/sodium-common.mixins.json b/common/src/main/resources/sodium-common.mixins.json
index df79a9fa07..d02f8fc296 100644
--- a/common/src/main/resources/sodium-common.mixins.json
+++ b/common/src/main/resources/sodium-common.mixins.json
@@ -63,6 +63,8 @@
     "features.render.immediate.buffer_builder.intrinsics.BufferBuilderMixin",
     "features.render.immediate.buffer_builder.sorting.MeshDataMixin",
     "features.render.immediate.buffer_builder.sorting.VertexSortingMixin",
+    "features.render.immediate.buffer_upload.GlBufferAccessor",
+    "features.render.immediate.buffer_upload.VertexFormatMixin",
     "features.render.immediate.matrix_stack.VertexConsumerMixin",
     "features.render.model.ItemBlockRenderTypesMixin",
     "features.render.model.item.ItemRendererMixin",