~5% is what Nouveau managed without GSP. According to a Phoronix forum post I can't find right now, with GSP it's something like 10% to 20% percent of the proprietary driver. Michael Larabel will surely publish numbers soon that are a bit more reliable.
It was ~5% because there was no reclocking whatsoever without GSP support.
Nouveau was never most performant driver, but developers still been able to achieve something like 50-80% performance on 6xx 7xx series cards before Nvidia started to signed firmware shenanigans.
It's not like I defending the driver performance, but considering for decades it was purely reverse engineering effort by skeleton team < 10 people their achievements are outstanding.
I agree. For years the effort was destined to only ever achieve 10% max of its potential performance. Also, there were architectural changes which probably rendered previous optimizations ineffectual.
To some degree this is probably just the vulkan driver and compiler being really, really immature. I expect that the gap will become a LOT closer in the next 6 months, or whenever they get past implementing vulkan 1.3 in the compiler and can put some work into cleanup.
Because you want your system installer or LiveUSBs to work without running GPU in VGA mode at 640×480. Also you get this 5% performance when GPU is clocked at 10% power draw.
Nouveau was already functional for desktop usage though, apart from certain bugs and limitations. If you just can't stand using the proprietary driver and don't need gaming or compute performance, go for it!
