New comment by jnbr on void-packages repository

https://github.com/void-linux/void-packages/issues/12885#issuecomment-514126336
Comment:
Shared memory shouldn't be an issue according to these numbers.
The graphics stack is identical to mine, so this doesn't seem to be the case either.

I'm not sure on how to debug this. I will push the update for firefox-68.0.1 later today, I don't expect it to fix your issues but it might be worth a try.