I run -current these days on most desktops. What I can say is that since 7.9, I have experienced smoother audio playback and system load overall on my decade-old laptop. So, it is likely that others will experience similar things when moving to 8.0.

Here are some.

http://bluhm.genua.de/test.html

Phoronix do test BSDs from time to time. But for different reasons I think OpenBSd missed twice. I hope to see the performance gap being close enough we can stop thinking it is very slow.