Paul wants to know how to get his SSD to run as fast as it did when he first got it. Leo says that SSDs can slow down a little over time and there's a command called TRIM, which can fix it if his OS supports it. It's like garbage collection. If he runs a defrag on the SSD, it will force the drive to TRIM. Leo recommends he do this very rarely though, because it can affect the even wearing of the drive. Will it make it that much faster? Not really. It might help a little, but he'll have to decide if it's worth the trouble.
It's not necessary to defragment a solid state drive. Traditionally, on a spinning hard drive, when data is written to the drive it's faster if all of the sectors are in order rather than scattered all over. Spinning drives have something called "seek time", which is the amount of time it takes for the read head on the drive to move to the next sector. If the read head has to move around a lot, that seek time adds up and the drive gets slower.