Is there a way to prevent faces of a CubeTexture from being rendered?
I was looking a bit through RenderTargetTexture but did not find a suitable point where to incept.
The reason for asking is that out of 6 surfaced I actually only need to render two and if I do not severly restrict the number of rendered meshes, the framerate drops to 7 fps in extreme situations.
My hope is that only rendering the two surfaces could massively speed up the rendering.

This is not possible so far but I am not against a mask being added here Babylon.js/packages/dev/core/src/Materials/Textures/renderTargetTexture.ts at master · BabylonJS/Babylon.js · GitHub

if you would like to create a PR ?

Thanks for pointing me to the right position. Before figuring out how to do a pull request, I tried with some type piracy (see below), This works somwhat but not really as hoped for. Lowering the refresh-rate (line 2 below) does increase the nominal frame rate, but strangely the percieved framerate is still as slow and this applies to the whole scene and not just the texture under question. This is weired, as I would have thought that line 2 applies only to this texture.
The face selection as implemented below has a problem: If you look at a surface at an angle or if the mesh is bend, there seems to be some blending effect going on (post-processing?). I am using Babylon’s reflection texture as the basis. Can this blending feature be turned off?

    const renderTargetTexture = lensTexture._renderTargetTexture
    renderTargetTexture.refreshRate = 2;
    const old_renderToTarget = renderTargetTexture._renderToTarget;
    function face_predicate(face) {return (!settings.disableSideRendering) || (face == 2 || face == 3)};
    const new_renderToTarget = function(face, useCameraPostProcess, dumpForDebug, dummy, camera){
        if (face_predicate(face)) { 
            renderTargetTexture._renderToTarget = old_renderToTarget;
            renderTargetTexture._renderToTarget(face, useCameraPostProcess, dumpForDebug, dummy, camera);
            renderTargetTexture._renderToTarget = new_renderToTarget;    
    renderTargetTexture._renderToTarget = new_renderToTarget;

I am not sure what blending you are speaking about :frowning: a pg would help better understanding I guess