pvs is still good for reducing overdraw and texture switches, but recalculating everything that's visible every frame is a lost cause.http://triptohell.info/moodles/junk/onedraw.zip
is my toy engine (or rather, renderer). source is included.
you can compile it to use either bindless textures or array textures to avoid texture switches.
you can use the number keys to switch between different bsp strategies. see for yourself which is best. for whichever map you're throwing at it.
I could claim massive framerate increases, but you wouldn't believe me anyway. see for yourself, just remember that it skips much of what quake engines do so its pretty much guarenteed to be faster...
it worked for me at the time, but I probably depended on nvidia's non-standard vulkan behaviour, so ignore that if its b0rked. and the bindless stuff requires nvidia to work properly, so that stuff might not fully work for you either. the other one requires gl3.3 or something.
anyway, bsp loading+rendering for bsp29+bsp2 can be found in gl_bsp29.cpp. see if you can figure the rest out.