I've recently started playing Skyrim again after a 5+ month break. I believe I was one of the first to encounter the Frame rate issues on PS3. It would literally lag at about 10FPS from start up. Now After patch 1.4 my 17mb save file dropped to 15mb and my lag was a lot better. Now I started playing again and I'm quite far in the MQ and mages college. Now I when I used to get horrendous lag with Fallout 3 and New Vegas I always wondered what a common factor was apart from the engine. I realised that If I go straight out to find every location in the game on Fallout 3,NV and Skyrim then my savefile soars. When I got these games the first thing I did was find every location. Now on this save even though I'm in about 30 hours now. My savefile is only 5000kb and rises up and down. I've only found 30 locations on this savefile. On my first Skyrim save, at 30 hours my save file was 9mb/10mb. I know that patches have helped reduce savefiles, but I thought I would add some input as I've battled through horrendous PS3 problems with Fallout 3 (which was the worst) Fallout New vegas and Skyrim.

Now I haven't had any FPS drops or freezes at all.

Yeah, this is what Josh Sawyer was talking about last year when he said that the way Bethesda's engine handled saved games was terribly inefficient in terms of memory. Basically every time you enter a location an index of the default for that location is created within your save file and everything you do in that location is saved as a bit difference from the default. Essentially this means that whenever a location is visited the game has to load that location twice, first the default and then apply the bit differences to make it the way you left it.

Factor in Bethesda's other bad memory design such as dragons and active quest characters being treated as near distance actors regardless of their global position and their lack of optimisation to our hardware and there's your reason for the frame rate.