diff --git a/src/cameras/CubeCamera.js b/src/cameras/CubeCamera.js
index c60e199c00cb0d..472247d20baea0 100644
--- a/src/cameras/CubeCamera.js
+++ b/src/cameras/CubeCamera.js
@@ -100,6 +100,8 @@ class CubeCamera extends Object3D {
 
 		renderer.xr.enabled = currentXrEnabled;
 
+		renderTarget.texture.needsPMREMUpdate = true;
+
 	}
 
 }
diff --git a/src/extras/PMREMGenerator.js b/src/extras/PMREMGenerator.js
index b85cf5d97fa64d..45fdb44447a840 100644
--- a/src/extras/PMREMGenerator.js
+++ b/src/extras/PMREMGenerator.js
@@ -124,9 +124,9 @@ class PMREMGenerator {
 	 * or HDR. The ideal input image size is 1k (1024 x 512),
 	 * as this matches best with the 256 x 256 cubemap output.
 	 */
-	fromEquirectangular( equirectangular ) {
+	fromEquirectangular( equirectangular, renderTarget = null ) {
 
-		return this._fromTexture( equirectangular );
+		return this._fromTexture( equirectangular, renderTarget );
 
 	}
 
@@ -135,9 +135,9 @@ class PMREMGenerator {
 	 * or HDR. The ideal input cube size is 256 x 256,
 	 * as this matches best with the 256 x 256 cubemap output.
 	 */
-	fromCubemap( cubemap ) {
+	fromCubemap( cubemap, renderTarget = null ) {
 
-		return this._fromTexture( cubemap );
+		return this._fromTexture( cubemap, renderTarget );
 
 	}
 
@@ -202,10 +202,10 @@ class PMREMGenerator {
 
 	}
 
-	_fromTexture( texture ) {
+	_fromTexture( texture, renderTarget ) {
 
 		_oldTarget = this._renderer.getRenderTarget();
-		const cubeUVRenderTarget = this._allocateTargets( texture );
+		const cubeUVRenderTarget = renderTarget || this._allocateTargets( texture );
 		this._textureToCubeUV( texture, cubeUVRenderTarget );
 		this._applyPMREM( cubeUVRenderTarget );
 		this._cleanup( cubeUVRenderTarget );
diff --git a/src/renderers/webgl/WebGLCubeUVMaps.js b/src/renderers/webgl/WebGLCubeUVMaps.js
index 3e14ff230914a2..f7c7bc3cd710d5 100644
--- a/src/renderers/webgl/WebGLCubeUVMaps.js
+++ b/src/renderers/webgl/WebGLCubeUVMaps.js
@@ -9,41 +9,58 @@ function WebGLCubeUVMaps( renderer ) {
 
 	function get( texture ) {
 
-		if ( texture && texture.isTexture && texture.isRenderTargetTexture === false ) {
+		if ( texture && texture.isTexture ) {
 
 			const mapping = texture.mapping;
 
 			const isEquirectMap = ( mapping === EquirectangularReflectionMapping || mapping === EquirectangularRefractionMapping );
 			const isCubeMap = ( mapping === CubeReflectionMapping || mapping === CubeRefractionMapping );
 
+			// equirect/cube map to cubeUV conversion
+
 			if ( isEquirectMap || isCubeMap ) {
 
-				// equirect/cube map to cubeUV conversion
+				if ( texture.isRenderTargetTexture && texture.needsPMREMUpdate === true ) {
+
+					texture.needsPMREMUpdate = false;
+
+					let renderTarget = cubeUVmaps.get( texture );
 
-				if ( cubeUVmaps.has( texture ) ) {
+					if ( pmremGenerator === null ) pmremGenerator = new PMREMGenerator( renderer );
 
-					return cubeUVmaps.get( texture ).texture;
+					renderTarget = isEquirectMap ? pmremGenerator.fromEquirectangular( texture, renderTarget ) : pmremGenerator.fromCubemap( texture, renderTarget );
+					cubeUVmaps.set( texture, renderTarget );
+
+					return renderTarget.texture;
 
 				} else {
 
-					const image = texture.image;
+					if ( cubeUVmaps.has( texture ) ) {
+
+						return cubeUVmaps.get( texture ).texture;
 
-					if ( ( isEquirectMap && image && image.height > 0 ) || ( isCubeMap && image && isCubeTextureComplete( image ) ) ) {
+					} else {
 
-						if ( pmremGenerator === null ) pmremGenerator = new PMREMGenerator( renderer );
+						const image = texture.image;
 
-						const renderTarget = isEquirectMap ? pmremGenerator.fromEquirectangular( texture ) : pmremGenerator.fromCubemap( texture );
-						cubeUVmaps.set( texture, renderTarget );
+						if ( ( isEquirectMap && image && image.height > 0 ) || ( isCubeMap && image && isCubeTextureComplete( image ) ) ) {
 
-						texture.addEventListener( 'dispose', onTextureDispose );
+							if ( pmremGenerator === null ) pmremGenerator = new PMREMGenerator( renderer );
 
-						return renderTarget.texture;
+							const renderTarget = isEquirectMap ? pmremGenerator.fromEquirectangular( texture ) : pmremGenerator.fromCubemap( texture );
+							cubeUVmaps.set( texture, renderTarget );
 
-					} else {
+							texture.addEventListener( 'dispose', onTextureDispose );
+
+							return renderTarget.texture;
+
+						} else {
+
+							// image not yet ready. try the conversion next frame
 
-						// image not yet ready. try the conversion next frame
+							return null;
 
-						return null;
+						}
 
 					}
 
diff --git a/src/textures/Texture.js b/src/textures/Texture.js
index 108642328b468a..49713629101fd0 100644
--- a/src/textures/Texture.js
+++ b/src/textures/Texture.js
@@ -70,7 +70,8 @@ class Texture extends EventDispatcher {
 		this.version = 0;
 		this.onUpdate = null;
 
-		this.isRenderTargetTexture = false;
+		this.isRenderTargetTexture = false; // indicates whether a texture belongs to a render target or not
+		this.needsPMREMUpdate = false; // indicates whether this texture should be processed by PMREMGenerator or not (only relevant for render target textures)
 
 	}