I believe if you use an SSD, the acccess times gradually get "slower" - more slower than a mechanical drive in fact - as there is no operating system taking care of trim, wear levelling etc. needed with an SSD. It may be fast initally - but after a few days of use, tests have shown that they are actaully a lot slower in PS3s (and there are a few websites detailing the tests)
The PS3 doesn't do anything that a PC would - so essentially the data on the SSD starts to degrade over numerous write/read cycles.