OT: Speeding up a slow computer

[AstralWanderer]

The only comparable option to a Windows reinstall (which doesn't itself require a reformat) is to try to remove obsolete files and registry entries manually - and deleting the wrong ones could require a reinstall anyway. I'd suggest biting the bullet, reinstalling Windows - and using software like Total Uninstall to keep track of (and clear out) the junk programs leave behind in future.

You could try using a registry cleaner, but these will only pick up a tiny portion of the junk present. Clearing out programs that run on startup that you don't need (and disabling unnecessary Windows services) would likely be of greater benefit, if you haven't already done this.