Considerable time spent in getProgramParameter

Hello Babylon folks,

I had an issue some times ago with BabylonJS spending too much time creating PBR materials (cf: https://forum.babylonjs.com/t/creating-a-lot-of-pbr-material)

I made some improvents to my code since but, when testing on low end computers this still took so much time.

After some investigations it turns out that this was due to chrome spending a lot of time in getProgramShader.

I unfortunately cannot give neither a repro or a javascript profiler trace.

I think that since there is already an option in engine to disable shader validations, we could add one to skip checking linking status because this is almost only intended for debugging purpose.