How old is your GPU/does it/the driver support async shader compilation? I've turned off shader pre-comp like two years ago because of this bug, never had any problems/lags with any games.

RTX 3060 mobile, nvidia blobs, default settings from the distro. Indeed, I disabled the shader cache at some point, for most single player games it was a good workaround, that was not the case for OW2 for some reason.