mmdb - 2009-01-01

Hi,
  I am writing a MSN robot program, using over 50 MSN accounts login and response contact's request. I found after the program had been run for few hours in daytime, the system became very slow, when I checked with system monitor, I found my prgram occupied around 25% CPU resource even when no message came in. this case didn't happen in night, I thought it might due to there is no much contact activities in night.
  Who can tell me how to avoid this. I guess there might be some thread run in background, which catch the events like contact go online and offline, however I don't know how to close those threads.