What version are you using? Prior to 1.2 there was a nasty perf bug with :hlsearch that caused it to be sluggish with 1) very large files or 2) a good number of files opened. The bug is mostly fixed in 1.2 but there are still a couple of corner cases. Those are addressed in 1.3 which will be released sometime next week. A beta drop is available here

https://github.com/downloads/jaredpar/VsVim/VsVim-1.2-Beta2....

As for crashes I'd love to hear about any you found. Feel free to send me email (hacker news alias at microsoft.com) or post an issue on github.

https://github.com/jaredpar/VsVim/issues