You finally pushed me into giving it a try. I started a 'Find in project' on a project with some multi-megabyte text files, and it not only gave me the Beachball of Death, it also was thrashing so heavily it took several minutes to get the terminal to respond enough to kill it.

I wasn't ready to give up, so I did some research and uncovered "Grep in Project", a replacement that does it right: http://henrik.nyh.se/2007/06/grep-in-project-command-for-tex...

I don't know what it is about "Find in Project" that drives text editor programmers to reinvent grep, badly. XCode suffered from terrible performance too for a long time.