The recently introduced Steam Deck framerate limiter option seems to add substantial input latency, according to a new online report.

　　Reddit user Dacvak recently shared on the Steam Deck subreddit a new report which highlights how setting any framerate limitation with the new option introduces input latency. The game used for the test is Rogue Legacy 2.

　　I decided to run latency tests on the Steam Deck (initially to see the added latency when connected docked to a TV with a wireless PS5 controller - btw, on my display, it added a mere 12ms of input latency), but in doing my tests, I discovered something interesting. Enabling the framerate limiter in the Performance menu adds an egregious amount of input latency, which scales somewhat linearly depending on the cap. These timings were captured with the Steam Deck undocked.

　　Upcapped: 31.8ms

　　60fps cap: 75.8ms

　　30fps cap: 145.9ms

　　50hz/uncapped: 32.5ms

　　50hz/50fps cap: 94.2ms

　　50hz/25fps cap: 186.1ms

　　40hz/uncapped: 34.3ms

　　40hz/40fps cap: 121.1ms

　　40hz/20fps cap: 232.0ms

　　Dacvak also tested running a game on Steam Deck with a built-in framerate cap such as Rocket League. In this case, there was no additional input latency. As such, using built-in framerate caps seems the way to go as of now, even if it may lead to uneven frame pacing or screen tearing when internal fps and screen refresh rate do not sync.

　　As requested below, I tested a game with a built-in frame cap option (not to be confused with vsync), then set the Deck to a matching refresh rate. In this case, I set Rocket League to a frame cap of 50fps (there was no option in RL for 40fps) and set the Deck’s screen refresh rate to 50hz.

　　This resulted in minimal to no increased input latency, which makes it the most viable solution when capping your framerate for performance/battery life reasons.

　　The Steam Deck SteamOS has been recently updated with the Beta 3.2 patch which added not only the option of changing the in-game screen refresh rate but also some other features such as an OS-controlled fan curve and more. You can find all the patch details by going here.