Q: clean up your mac?

Whatever you do, do not download or install any product claiming to "clean up" or "speed up" or "optimize" your Mac. Without exception, they will do the opposite. If you already did, you found the problem. Fix it.

If it is only Web browsing that seems to be slower than it used to, that is usually the result of such pages becoming ever more demanding of hardware and bandwidth. Aside from buying more memory, there is little you can do to cope with such so-called progress.

If you're experiencing general slowdowns or "freezes" unrelated to Internet activity, the problem may be related to your computer or the software you installed and is something you may be able to fix, or at least improve. Aside from hardware failures and software that you install, including OS upgrades, there is no reason that your computer should not work exactly as well as the day it was built.

Without a more specific description it is difficult to provide specific guidance. Read the following to determine if something may apply to your concern:

General Mac maintenance (including how to clean it): Tips to keep your Mac in top form

General purpose Mac troubleshooting guide: Isolating issues in Mac OS X

Creating a temporary user to isolate user-specific problems: Isolating an issue by using another user account

Memory limitations: Using Activity Monitor to read System Memory and determine how much RAM is being used

Identifying resource hogs and other tips: Runaway applications can shorten battery runtime

To identify potential hardware problems: Apple Hardware Test

John Galt has given you excellent advice.  The only thing he neglected to tell you is to use a damp, soft lint free cloth to clean your MBP.

Ciao.