Something is wrong on your end if you can't mix 20 dash with 8 rounds in less than 2 hours. Or else your settings are made to wait a long time between rounds.
Mixing is not at all as stable as it needs to be. It hangs when I mix almost every time and I need to restart my client or zap the wallet to get it going again.
I do wish there was more focus on polishing the current release. I have the feeling that there might be a stampede into Dash before Evolution is ready.