Wanted to chime in here. I just installed the 10.10.4 public beta on my machine and with transparency turned off, the UI lag is *almost* nonexistent and very acceptable for my standards. Here's what my setup is like:
Base (1.1) model
1680 x 1050 @ HiDPI resolution (There's a thread on this specific board that details how to unlock this for RDM)
~6 spaces open at all times:
Slack (fullscreen)
Sublime Text (fullscreen)
Dash Docs (fullscreen)
Desktop 1: Safari only
Desktop 2: Terminal, Xcode, iOS Simulator
Desktop 3: Omnifocus 2, Evernote, Messages
Background apps: Bartender, LaunchBar, Fantastical 2, Dropbox, 1Password, Spectacle.
The transition when swiping spaces is almost lag-free.
Entering Mission Control stutters a slight bit, swiping spaces in Mission Control is almost lag-free, and settling on a space from Mission Control is also almost lag-free.
Enabling transparency reduces performance by a small (but noticeable) bit. Anything that was 'almost lag-free' produces noticeable lag in that case.
Hope this was helpful!
Base (1.1) model
1680 x 1050 @ HiDPI resolution (There's a thread on this specific board that details how to unlock this for RDM)
~6 spaces open at all times:
Slack (fullscreen)
Sublime Text (fullscreen)
Dash Docs (fullscreen)
Desktop 1: Safari only
Desktop 2: Terminal, Xcode, iOS Simulator
Desktop 3: Omnifocus 2, Evernote, Messages
Background apps: Bartender, LaunchBar, Fantastical 2, Dropbox, 1Password, Spectacle.
The transition when swiping spaces is almost lag-free.
Entering Mission Control stutters a slight bit, swiping spaces in Mission Control is almost lag-free, and settling on a space from Mission Control is also almost lag-free.
Enabling transparency reduces performance by a small (but noticeable) bit. Anything that was 'almost lag-free' produces noticeable lag in that case.
Hope this was helpful!