First of all, let me state I have not experienced the lag (yet), and I hope to keep it this way.
Because of this I've been eyeing the forums to "predict" when it could happen to me.

Obviously the cause seems to be savegame sizes, but I've also seen enough posts stating people with a small size experiencing tremendous lag and people with big filesizes without the lag.

So I wondered, could the lag be caused by some sort of in-game event (e.g. quest, item, certain skill or perk, whatever)?
This would make sense for most people to experience this with bigger savegames, since that states you've put more hours in and did more things, so the chance you'd hit it would be greater than people who played less.
It also would make sense for people with few hours in and small savegames, since there's still a chance you triggered it.

Hope I get my point across.

Again, just a theory, but what were the last things you did/acquired when you started to notice the lag?

I don't see why a particular event in the game would suddenly magically cause it to lag. It's just related to file size, and the fact the ps3's RAM can't handle it as the cache is not clearing fast enough. The reason why people experience the lag at different points is twofold:

a) Everyone's game is different, and so even though two files are the same size, it may be that one file is taken up by a lot of- say- corpses and the other with regular objects, and possibly corpses causes the system to slow down more than normal objects

b ) Noone has been able to measure it objectively. Some people might have lag but simply not notice it. Others might be exaggerating. Others might not have gone into areas where the main amount of lag occurs (eg: outside Whiterun)

I dont think so, when i started a new char and everything i didnt follow the main quest line or the usual side quests i started in whiterun (like i didnt do the companions for my mage but did for my 2 hand warrior) same crap everyy time. now im tryin to make a thief and instantly go for the dark brotherhood quests (involves skippin everything and goin straight for windhelm)

@ Squoosh: Your statement a) supports my theory.

I actually think this is a strong possibility. A corrupt file could cause these types of problems.

I am a bit confused by the new claim from some people experiencing the problem that those who aren't really are but they "just don't notice it". I have seen it in this thread, and a few others. Is the lag game breaking or not? I would think game breaking lag would be pretty hard to miss.

So why just don't compare the statistics and solved/opened quests? If such an events would exist, theres a pretty good chance, that it is something more important than just wandering around or cleaning some dungeons. Maybe these statistics would show a shared "event" for the users with these problems and them without.