Valve recently released a new beta patch for Steam Deck that adds experimental support for changing the screen refresh rate of games on the well-received handheld, but it reportedly comes with a major caveat. Tests conducted by Dacvak suggest that limiting the frame rate using the new feature, which can be accessed via a slider in SteamOS’ Performance tab, can add a substantial level of input latency. The level of latency may be as high as over 200 milliseconds depending on the setting.
- 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
PSA: Enabling the Framerate Limiter adds substantial input latency (timings inside) (r/SteamDeck)
I conducted the latency tests using an iOS app called “Is It Snappy?”, which captures video at 240fps and lets you pin a starting and endpoint to calculate the differential in ms. Because this is a 240fps capture, there’s always a +/- 4ms margin of error, and so to compensate for this, I take 5 individual timings and average them out (represented in the data above).
My latency timing starting point is when the button is fully pressed, while the ending point is the first visual change on the screen. (Referred to as “button-to-photon” latency timing.) All of my tests were done in Rogue Legacy 2 in the settings menu, as that was the lowest latency and most consistent game I had tried.
The conclusion is that enabling ANY framerate limiter cap adds a truly significant amount of input latency. However, the Steam Deck (running uncapped) has a truly impressive button-to-photon already, so enabling the 60fps cap is fully playable in most games, while the 30fps cap is playable for some games. These are my opinions, and obviously your tastes will determine your personal thresholds.
Valve added experimental support for changing the in-game screen refresh rate on the Steam Deck as part of its SteamOS 3.2 beta patch released last Wednesday, April 29. The feature had been anticipated by users who were looking for a way of increasing playtime on the Steam Deck, as previous reports had suggested that limiting frame rate was an effective way of extending the battery life of the handheld.