Q: how can I improve the performance of my macbook pro?

Read thomas_r's -> Mac Performance Guide. It's an excellent overview.

Clinton

MacBook Pro (15-inch Late 2011), OS X 10.??, 16GB Crucial RAM, Crucial M500 960GB SSD, 27” Apple Thunderbolt Display

Try a boot in Safe Mode and see if its 3rd party software thats causing an issue!

OS X: What is Safe Boot, Safe Mode

Also this comes in handy to find issues

..Step by Step to fix your Mac

Please describe the problem in as much relevant detail as possible. The better your description, the better the chance of a solution.

For example, if the computer is slow, which specific actions are slow? Is it slow all the time, or only sometimes? When did it start to be slow? Did you change anything just before it started? Have you seen any alerts or error messages? Have you done anything to try to fix it? Most importantly, do you have a current backup of all data? If the answer to the last question is "no," back up now. Ask if you need guidance. Do nothing else until you have a backup.

Download and post an EtreCheck Report:

http://www.etresoft.com/etrecheck

It may provide some very useful information regarding your MBP.

Ciao.