The Destiny 2: Beyond Light expansion made a very positive impression on us, but it also led to reduced performance for some players. The first post in this Reddit thread, for instance, says Beyond Light took the player's game from 100-130 fps to 45-55, with GPU utilization pushing 100%. A large number of responses claim similar problems.
Bungie said in November 2020 that it was looking into reports of "issues related to low performance on PCs," and established a mega-thread tracking updates and possible workarounds. Now, courtesy of the most recent This Week at Bungie update, we've finally got an idea of what went wrong, and why Bungie hasn't made a show of jumping in with both feet to fix the problem.
"Performance testing and optimization on PC is very complex due to the different combinations of hardware, software, and in-game settings. With the release of Beyond Light, we made some major engine changes while working from home," Bungie wrote.
"One of the unfortunate consequences of working from home is that we no longer had access to our PC compatibility lab to do in-depth testing on the performance impacts of our changes. Partially as a result of this, the update introduced regrettable performance decreases on some PC configurations – some configurations more than others."
Developers have been making fixes in every update since then, but getting things back to where they were has been a slow process because Bungie has to rely on external partner testing and feedback from the live game to determine what sort of impact the changes have. That's why it hasn't been talking about the work it's doing, even in the patch notes: "Because of the difficulty in predicting how much each change will improve performance, we've been reluctant to promise a fix, even though we are making regular performance optimizations," Bungie said.
The good news is that Destiny 2's performance is now "close to what it was before Beyond Light for some PC configurations." That's not the most precise metric of all time, but at least it's an improvement. And it isn't finished yet: Bungie said it's continuing to work on the problem and is "optimistic about the future."
Bungie also addressed issues with enemies being more "teleporty" since the release of Beyond Light, saying that it made changes to outgoing bandwidth limits on its servers that should reduce the effect, although some activities won't be impacted by the change.