Why don't I see a significant boost in performance moving to SSD on MacBook7,1?
I had the same issue with the Samsung SSD. The main issue appeared to be with spotlight indexing. After installing the SSD the drive would not index. If you click on the spotlight search does it show indexing with a progress bar and estimated time with no estimate? If so this answer will help fix your issue. I tried several fixes before I solved the issue. 

To turn off indexing you can do the following:


open the terminal app
type sudo mdutil -Ea -i off 


This should help with performance issue if indexing is the cause. Thanks svenper for the "E" addition.