Performance regression in Baldur's Gate 3 when used with aftermarket internal screen

[cheater]

DeckHD and the upcoming DeckSight are aftermarket replacement screens for the Steam Deck LCD. Sreen replacements are becoming more and more popular.

When playing very demanding titles such as Baldur's Gate 3 on the DeckHD, it is customary to run them at 960x600, which can integer scale up to 1920x1200. With FSR 1.0 scaling, the games look sharp and very pretty. This works really well in titles like God Of War and Jusant.

However, Baldur's Gate 3 does not allow this resolution.

It is not available within the game's options, and it is also not available via the "Game Resolution" dropdown in the Game Properties dialog of SteamOS. That said, 800x600 is available, and fully playable, so it's not like the resolution of 960x600 is "too small" for the game or anything like that.

As Baldur's Gate 3 is pretty much the Steam Deck "system seller" game, I was hoping this could get some good attention.

I have already mentioned the missing resolution in the Game Properties dialog in issue #1791, but as this particularly affects Baldur's Gate 3 in more than one way, I decided to add a separate bug report just for this game.

I would appreciate it a lot if a fix could be implemented within a short time as this issue stopped me dead in my tracks in the middle of a game play-through. Thank you very much.

[kisak-valve]

Hello @cheater, changing your hardware specs to something that requires substantially more GPU power to give equivalent results is not a regression. This is not a separate SteamOS issue from #1791.

[cheater]

@kisak-valve while I agree with the statement that "changing your hardware specs to something that requires substantially more GPU power to give equivalent results is not a regression", that is not the case here. The idea is to play the game at 960x600, which is a resolution which should require substantially less power to give equivalent results. However, SteamOS requires playing at a higher resolution than that, lowering performance. Therefore, this is a situation where a small oversight in SteamOS is at fault for poorer performance that could otherwise be achieved.

The immediate fix is to add a single resolution to an existing list and therefore it is not a duplicate of #1791, which is more involved than the immediate fix for this issue. In addition, Baldur's Gate 3 does not internally pick up the resolution of 960x600, even though almost every other game does, and even though BG3 itself allows 800x600. Why does it not do that? Could it be due to the compatibility layer? Who knows - this needs to be investigated.

For this reason, can you please re-open this issue and investigate it.