If your start menu has the small icons instead of large, that's the reason for the lag, although I've not found any solution for that. It's on my list of things to research over the holiday break this week.
As for the crashing, that's not something I've experienced or heard about. Can you try to pin down whether it's crashing as a result of a consistent action or tab (entering or leaving), and can you identify any other Manila/TouchFLO-based tweaks you've enabled?
