There shouldn't be anything different in that scene to how I am loading other scenes in the game. Even the post-processing effects in the game have basically been on since the game starts.
Is this the FIRST stairs sequence or the SECOND? The SECOND does introduce an animated overlay that may be taxing to older PCs.
I have tested this game on a firefox browser using an arch linux machine, but haven't been able to try it on other OSes outside of Mac, Windows, and Android.