WebGPURenderer: Remove per-draw WeakMap.set allocation in pipeline dedup.

`WebGPUPipelineUtils.setPipeline` tracked the active pipeline per pass
encoder via a WeakMap. Pass encoders are created fresh every frame, so
each pipeline change fired `_activePipelines.set( pass, pipeline )` —
allocating a new entry hundreds of times per second. Sampled heap
profile attributed ~64 KB / 10 s to this one line on webgpu_backdrop_water.

We already track the active pipeline in `currentSets.pipeline` (render)
and can do the same on the compute group's data entry. Inline the
dedup at both call sites, delete the WeakMap, delete the method.

Bonus: use an Array for `currentSets.attributes` instead of `{}` and
reset with `.length = 0` — avoids the `for…in / delete` loop in
`_resetCurrentSets` that caused hidden-class transitions.

Measured on webgpu_backdrop_water (Inspector stripped, 10 s, 1 KB
sampling): `update @ Animation.js:70` subtree 402 KB → 341 KB (−15%).
`animate` child subtree 135 KB → 61 KB (−55%).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: RenaudRohlinger

src/renderers/webgpu/WebGPUBackend.js

@@ -50,7 +50,7 @@ const _depthViewOptions = { dimension: undefined, arrayLayerCount: undefined, ba
 
 function _resetCurrentSets( sets ) {
 
-	for ( const key in sets.attributes ) delete sets.attributes[ key ];
+	sets.attributes.length = 0;
 	sets.bindingGroups.length = 0;
 	sets.pipeline = null;
 	sets.index = null;
@@ -908,7 +908,7 @@ class WebGPUBackend extends Backend {
 
 				} else {
 
-					bundleSets = { attributes: {}, bindingGroups: [], pipeline: null, index: null };
+					bundleSets = { attributes: [], bindingGroups: [], pipeline: null, index: null };
 					renderContextData.bundleSets[ i ] = bundleSets;
 
 				}
@@ -952,7 +952,7 @@ class WebGPUBackend extends Backend {
 
 		} else {
 
-			renderContextData.currentSets = { attributes: {}, bindingGroups: [], pipeline: null, index: null };
+			renderContextData.currentSets = { attributes: [], bindingGroups: [], pipeline: null, index: null };
 
 		}
 
@@ -1603,13 +1603,19 @@ class WebGPUBackend extends Backend {
 	compute( computeGroup, computeNode, bindings, pipeline, dispatchSize = null ) {
 
 		const computeNodeData = this.get( computeNode );
-		const { passEncoderGPU } = this.get( computeGroup );
+		const groupData = this.get( computeGroup );
+		const { passEncoderGPU } = groupData;
 
 		// pipeline
 
 		const pipelineGPU = this.get( pipeline ).pipeline;
 
-		this.pipelineUtils.setPipeline( passEncoderGPU, pipelineGPU );
+		if ( groupData.currentPipeline !== pipelineGPU ) {
+
+			passEncoderGPU.setPipeline( pipelineGPU );
+			groupData.currentPipeline = pipelineGPU;
+
+		}
 
 		// bind groups
 
@@ -1736,8 +1742,12 @@ class WebGPUBackend extends Backend {
 		const hasIndex = ( index !== null );
 
 		// pipeline
-		this.pipelineUtils.setPipeline( passEncoderGPU, pipelineGPU );
-		currentSets.pipeline = pipelineGPU;
+		if ( currentSets.pipeline !== pipelineGPU ) {
+
+			passEncoderGPU.setPipeline( pipelineGPU );
+			currentSets.pipeline = pipelineGPU;
+
+		}
 
 		// bind groups
 		const currentBindingGroups = currentSets.bindingGroups;
@@ -2365,7 +2375,7 @@ class WebGPUBackend extends Backend {
 
 		} else {
 
-			renderContextData._bundleCurrentSets = { attributes: {}, bindingGroups: [], pipeline: null, index: null };
+			renderContextData._bundleCurrentSets = { attributes: [], bindingGroups: [], pipeline: null, index: null };
 
 		}
 

src/renderers/webgpu/utils/WebGPUPipelineUtils.js

@@ -38,35 +38,6 @@ class WebGPUPipelineUtils {
 		 */
 		this.backend = backend;
 
-		/**
-		 * A Weak Map that tracks the active pipeline for render or compute passes.
-		 *
-		 * @private
-		 * @type {WeakMap<(GPURenderPassEncoder|GPUComputePassEncoder),(GPURenderPipeline|GPUComputePipeline)>}
-		 */
-		this._activePipelines = new WeakMap();
-
-	}
-
-	/**
-	 * Sets the given pipeline for the given pass. The method makes sure to only set the
-	 * pipeline when necessary.
-	 *
-	 * @param {(GPURenderPassEncoder|GPUComputePassEncoder)} pass - The pass encoder.
-	 * @param {(GPURenderPipeline|GPUComputePipeline)} pipeline - The pipeline.
-	 */
-	setPipeline( pass, pipeline ) {
-
-		const currentPipeline = this._activePipelines.get( pass );
-
-		if ( currentPipeline !== pipeline ) {
-
-			pass.setPipeline( pipeline );
-
-			this._activePipelines.set( pass, pipeline );
-
-		}
-
 	}
 
 	/**