Reports of Skyrim players encountering severe lag, particularly on PlayStation 3, continue to roll in even after the most recent patch was said to resolve those issues. From what we know this stems from the increasingly large size of players' save game files, a problem that may take a big investment to fix.
Obsidian Entertainment's Josh Sawyer offered up some thoughts on Skyrim's technical issues recently in response to questions he received on Formspring. Sawyer works as a project director at Obsidian, which developed Fallout: New Vegas using the same engine Bethesda used for its most recent game before Skyrim, Fallout 3. While Skyrim runs on a different set of technology, Sawyer does provide some insight into why the problem with lag hasn't been fixed more quickly and why the PS3 version has been especially troubled by it.
"The Xbox 360 has a unified memory pool: 512 megs of RAM usable as system memory or graphics memory," Sawyer wrote. "The PS3 has a divided memory pool: 256 megs for system, 256 for graphics. It's the same total amount of memory, but not as flexible for a developer to make use of."
"As with Fallout 3 and Skyrim, the problems are most pronounced on the PS3 because the PS3 has a divided memory pool," he wrote in response to another question.
Both Fallout 3 and New Vegas suffered from a similar issue as Skyrim, so this isn't the first time Sawyer or Bethesda have heard about it.
The size of save games tends to become very large over time due to "bit differences." Sawyer explains these are used to keep track of anything that has been changed in the game, such as an enemy being killed or looted, and in large games like Fallout or Skyrim, these changes add up over time to number in the thousands -- and all of them have to be stored in your save file and then loaded when you play the game.
Asked why something like this hadn't already been resolved, Sawyer described it as "an engine-level issue with how the save game data is stored off as bit flag differences compared to the placed instances" on the game disc.
"It's not like someone wrote a function and put a decimal point in the wrong place or declared something as a float when it should have been an int," he continued. "We're talking about how the engine fundamentally saves off and references data at run time. Restructuring how that works would require a large time commitment. Obsidian also only had that engine for a total of 18 months prior to F:NV being released, which is a relatively short time to understand all of the details of how the technology works."
Keep in mind these response were authored in November, before the latest patch was announced, not to mention the fact that Sawyer doesn't work for Bethesda.
The patch Skyrim received on all three platforms last week didn't work as intended -- users continued to report sometimes-crippling lag in addition to new problems like backwards-flying dragons and resistances being ignored. Bethesda has since said it plans to have a patch out this week to address those two new problems, while some users have found that frequently restarting the game or disabling autosaves can improve performance.
"We all know this is a huge game, and everyone has a different experience," a message from Bethesda stated last week. "We'll continue to do everything we can to make the game better and better for as many people as possible every day. We've also realized that with the millions upon millions of people playing Skyrim, we need to treat our updates with greater care. If we get too aggressive trying to fix a minor issue, we run a risk of breaking something larger in a game like this."