Witch 4.5.4 is out now, with a number of minor fixes and improvements—check the release notes for all the details. The biggest improvement is probably for those who use Spaces: Switching between them should be more reliable now, especially when at least one of the apps involved has windows on more than one Space. (Switching across Spaces is still slower than non-Spaces switching, but we can’t do anything about that, due to how we have to switch Spaces.)
As always, you can update directly from the System Settings panel (on the About tab), or by downloading a new copy of Witch from our site (you won’t lose your settings).