SteamOS 3.5.5 has been released to the Stable channel for Deck with the following changes: Display The default color rendering for Steam Deck LCD has been adjusted to emulate the sRGB color gamut, resulting in a slightly warmer and more vibrant color appearance. Added Settings -> Adjust Display Colo...
Basically you could only previously get good emulation performance if you disabled multithreading because of a bug, but now that's been resolved and you don't need to. It should help with those systems a bit, yes.