WebGPURenderer: Reduce per-frame allocations in render & compute paths

src/renderers/common/Renderer.js

@@ -650,6 +650,16 @@ class Renderer {
 		 */
 		this._compilationPromises = null;
 
+		/**
+		 * A reusable single-element array used by `compute()` when called with
+		 * a single compute node. Avoids allocating a fresh `[ computeNodes ]`
+		 * array on every call, which would otherwise churn the GC each frame.
+		 *
+		 * @private
+		 * @type {Array<?Node>}
+		 */
+		this._computeSingleton = [ null ];
+
 		/**
 		 * Whether the renderer should render transparent render objects or not.
 		 *
@@ -2724,7 +2734,18 @@ class Renderer {
 		const bindings = this._bindings;
 		const nodes = this._nodes;
 
-		const computeList = Array.isArray( computeNodes ) ? computeNodes : [ computeNodes ];
+		let computeList;
+
+		if ( Array.isArray( computeNodes ) ) {
+
+			computeList = computeNodes;
+
+		} else {
+
+			this._computeSingleton[ 0 ] = computeNodes;
+			computeList = this._computeSingleton;
+
+		}
 
 		if ( computeList[ 0 ] === undefined || computeList[ 0 ].isComputeNode !== true ) {