According to player feedback, the new frame rate cap option on the Steam Deck console seems to have caused some serious input lag. A user Dacvak recently posted feedback on this problem. He tested it with Rogue Legacy 2 and the statistics are as follows:
- Unlimited: 31.8ms
- 60fps cap: 75.8ms
- 30fps cap: 145.9ms
- 50hz/no upper limit: 32.5ms
- 50hz/50fps upper limit: 94.2ms
- 50hz/25fps upper limit: 186.1ms
- 40hz/no upper limit: 34.3ms
- 40hz/40fps upper limit: 121.1ms
- 40hz/20fps upper limit: 232.0ms
Dacvak also used Steam Deck to test Rocket League, which has a framerate cap option in the game but found no input lag. In other words, if this function is built into the game, it is no problem to use it, but it may cause the frame rate not to be asked or the screen to tear.
I don’t know if Valve will take this issue seriously and test and fix it.