Apps are installed to different places, depending on what they do, whether they're optified, what data files they include, etc. Moving them will also depend on the app - if it's a single large binary, library, or datafile, or a directory full of files, then it's easy enough to move. Some applications contain hundreds of files installed all over the place though, making it far more difficult.

And, of course, if an app has been optified then all of this should have been taken care of already.