Don't know if they are the best; but, I like
PrivaZer or
CCleaner.
What
@sneekypeet said, it would help...
Without any info...
If you are not worried about or care about saving energy... set your power options to the High Performance or Ultra High performance.
Go through your startup (using
taskmanager,
autoruns, or your favorite app) and turn off any not needed apps that start and run, like java updater, adobe updater, etc.
Get rid of any junk and
free up as much drive space as possible... then defrag your drives, if you don't have it set to do so, already.
Before you go deleting and changing things... make a clone of your drives or some other backup option... if not, you might be looking at a complete re-install. At least it would fresh and clean.
Good luck.