just wanna ask something here.....recently my firefox browser loading speed of website is becoming more n more slower than usual.....n this happen after my bitdefender license was expired when i was away from my computer...I have already install back a new antivirus (ESET NOD32) and quickly scan my computer for infected spyware or virus but it showing 0 infection...but still my firefox browser speed didnt recover at all as well as my IE7....so are my computer being infected by spyware or virus??do i need an anti-spyware?

pls help....thanks