i just downloaded secondlife and it runs very slow how do i fix that

I’m trying to delete some old programs i installed in my computer n i need to find a free Registry Cleaner to use so can u guys please help me? thanks

This has happened before but it was always related to software. I have put no new software on. I have done a diagnostic and it says everything is ok. This is a Dell Inspiron 9300. My anti virus says no viruses and my spysweeper says no spyware. I did get a message a couple of days ago from my antivirus that said it had quarrantined something that could possibly be a virus. I deleted it and scans since then come up clear. I am also getting a message from my fire wall that says something about ICMP Echo Request (‘Ping’) from (IP addy) and it’s blocking it. Any ideas?
I use avg antivirus, spysweeper, and zone alarm firewall.