I find that defrag the RAM, dump the cookies (Mozilla has a great tool for this) and fixing registry errors keeps my pc (3of them) running super fast.
The program I've used for years is 'system mechanic' costs 10-20 a year and in addition to simplifying all of the above it also has several other great pc health tools.
The cool feature is its health meters look like a tach & speedo guages!
Paired with Kaspersky internet security and malware/bites we have had zero problems (accept for one occasion where I had a HD issue and had to call SlowDave)
Anyway, that's what works for us.
Hope you're not using explorer still, my wifes work computer runs explorer and demands constant attention!
.02
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Former Test driver & Production Manager Singer Vehicle Design
2009 Cayenne GTS, '81 911SC RoW Targa (lot's of goodies), '86 535csi, '84 633 csi (turbo charged-sold)
, '68 912 Targa (sold)
, '69 911E (sold)
"Dream it, Believe it, Decide it, DO it "