Something very common in people's Macs is to install .pkg packages and then uninstall them too roughly and without taking into account the files or preferences that can be left out there taking up space and processing time on our Mac.
The solution is DesInstaller, a program with a really bad interface but that works like a charm to get rid of the .pkg packages installed on our Mac and all their files, leaving the installation clean.
There is a beta of version 3 that hangs me, perhaps because of the 64-bit, but it is supposed to have a better interface than 2.
Link | Uninstaller