they don't exist. back in the days of dial up tweaking the modem settings could make a substantial difference to the performance, but not these days. While there are tweaks you can make, they have very little impact. Programs that claim to speed up your computer by significant amounts are fake. Defragging your hard disk can have the biggest impact, but only if its badly fragmented.
Do as Loony stated then you might want to look into upgrading your internet to a higher level from your ISP.
After you do what Loonylion suggests,download CCCleaner from filehippo which gets rid of a lot of junk files.I would also use Superantispyware and Malwarebytes in case malware is present. The 3 x programs are all free.