I found newest beta much slower than previous. Working, still possible is very painfull and needs lot of patience. I didn't change anything lately, except instaling new beta, file isn't very complicated, computer was restarted. Working with last beta on same setup was flawless. There in no difference between rendering on GPU or WARP.
Sadly I cannot give say more, but maybe I'm not the only one. If you have this problem, try to disable in Preferences/Performance/Hardware Acceleration, works for me!