I purchased App Zapper probably over ten years ago, and while it doesn’t seem to have been updated in forever, it still works. Another choice, curated by Nikhil Vemu at Mac O’Clock, is the uninspired-sounding Advanced Uninstall Manager.
These uninstallers go a step further than Apple’s suggested (and simpler) method by also removing anything the app created in other directories, typically your ~/Library and /Library directories (which Apple obscures from the user).
I don’t know if deleting apps using an uninstaller will actually speed up your Mac, as Vemu suggests. It can, however, uncover large data libraries of apps that create them. For example, my installation of MailMate takes up a whopping 8 GB of data in ~/Application Support.
