If you read the forums before buying the pro version you would know that the pro version isn't different from the actual free version, except that the pro version doesn't have the "Buy pro advertisements".
Normally, if you bought it it's because you chose to contribute to the developpement of an otherwise free app.
Also, you should know that the performance is very variable from computer to computer and that some people experience virtually no problems when others experience only problems.
You can't expect it to be on a Turbocharged status all the time: sometimes you'll be on poor when other times you'll be excellent or better.

Patience is indeed a virtue.