No your stats are stored serverside on each server you play, they are tracked by your steam id. When re-installing steam dont bother doing the whole thing.
Open your steam folder, goto steamapps then goto your user name. In there is a folder called counter-strike source, rename it to something else and then launch CSS. You will now be playing a fresh "install" of CSS, see if you still suffer from the issue. If you do then it most likely caused by your drivers or another application on your computer consuming a large portion of your CPU. Do you have any 'desktop search' apps installed? i.e. Nero Scout, Google Desktop
Yeah steam updates your games automatically, in your case this may actually be the cause of the problem. Unfortunately there is no way to rollback updates on Steam so you can't test the old version out. I would check to make sure your "advanced" video settings are set correctly inside CS:S (Try disabling HDR if it's enabled)
A forum community dedicated to tech experts and enthusiasts. Come join the discussion about articles, computer security, Mac, Microsoft, Linux, hardware, networking, gaming, reviews, accessories, and more!