Thank you, I did that and its much better. The first time I launched iTunes took 11 seconds, but after I quit it, each time I launch it again it takes less 3 seconds, just like in Apple store.25 sec to open iTunes is not normal.
Use Disk Utility (Applications / Utilities) to check / repair the disk and repair the permissions, restart the Mac. What is the delay now ?
Yes, you are right.I think another important thing before was the number of applications open at one time, especially many Firefox tabs, which include some add-ons as well. And the fact that I almost never shut down or restart the Macbook.