In truth the defrag and temp file suggestions will help only marginally
with your problem, if at all. However, I believe these are good things
to do for optimum overall PC performance. Your best bet is to close
unnecessary programs, and if needed, disable unnecessary services,
reboot, and try again. On the other hand, on a system equipped with
minimal RAM there is no substitute for increasing the physical RAM.
Temp files are handled rather poorly by Windows. When I had W98 there
were only a few places to check.
Then I got XP and found many more. I pretty much nailed the locations XP
Pro used, which was interesting because the built-in disk "cleanup"
facility ignored these locations. I had to create an elaborate batch
file to loop through various fixed locations and (variable) user
accounts to delete all the temp files I could find.
Now I have Vista something-or-another and everything has changed again.
I'm not even sure temp file usage is even constant from one installation
to the next, let alone between major or minor versions of Windows. I
have not revived/revised my batch file for Vista yet.
Internet files are probably easier to deal with since your browser can
control how these cache files are managed. How depends on the browser,
but in general if you root around in the menus you should be able to
find out how. With IE temporary internet files can be zapped though the
disk "cleanup" utility (right click any drive letter and poke around).