Steven C:
It's scanning all the processes in your system and checking them against a blacklist of over 150,000 processes (run your cursor over the TeaTimer system tray icon). If you are running the latest version of TeaTimer (1.6.2.23), it builds a Cache file (ProcCache.sbc) so that subsequent scans when TeaTimer starts use less CPU time except the first time is starts after an update.