One single flash device is not particulary fast by today's standards, a HDD - even a laptop drive - is almost guaranteed to be faster and perhaps considerably so, on a purely technical level. Of course actual implementation in the PS3 can affect things considerably, but I doubt it has any major impact regardless...Because the slims have to read their firmware off of the hard drive, things like playing Blu-ray movies from power-on is bound to take a bit longer.