Another theory concerns where Bethesda store this database. The split-pool RAM architecture on PS3 is more constrictive than it is on 360, and this is clearly a RAM-intensive game. We wonder if the save game resides in the graphics RAM instead of the XDR, which Cell addresses much more quickly. Bandwidth between the PS3 CPU and VRAM is a mere 16MB/s, compared to the 22GB/s access the 360 has to its unified 512MB of GDDR3
[...]the most likely explanation is that an advanced Skyrim gameplay state - like the 65 hour one we tested - proves to be too much for the garbage collector, or memory defragmention method, struggling to cope with the multitude of gameplay elements that have been altered from the default "virgin" state stored on the hard drive. To test the possibility of this, we tried loading our 65 hour save and playing with it for 30 minutes, and then directly loading our new character save from the menu - the result being that the stuttering does indeed carry straight over to our virgin save. It suggests that memory has been allocated that the garbage collector cannot reclaim, which isn't flushed when the player returns to the menu screen and starts the game anew.