It keeps hanging briefly when I change code, for instance highlighting a section of code to copy and paste it will freeze, sometimes long enough for it to register as “not responding” before resuming. I can then edit briefly before it freezes again for a few seconds.
I don’t use Monodevelop because I find it incredibly slow and unresponsive. I use Unitron instead (it is included with Unity on a Mac). While it doesn’t have as many features, it is very responsive.
I just started having this problem today. I tried disabling most of the MonoDevelop add-ins, but it didn’t help. For now I’ve switched to notepad++ :-p