I was contemplating the fact that inflicting frame per second restrictions is not ideal in regards to latency and performance since a monitor still has a chance to show something sooner (assuming no vertical sync which is mainly for stability).
However, it occurred to me that process might have ramifications on audio subsystems (or also input devices), assuming frames per second also governs the global loop of the engine itself (the case in almost all 3D accelerated applications).
Do audio cards/audio devices on an operating system have a concept of “Hertz” that might be related? Do we assume the faster the global loop of the application the better the latency for the audio subsystems?
Audio is not typically affected at all. The audio has a separate buffer which you fill up in advance, maybe a hundred milliseconds or more, and the sound card plays back from that regardless of what your game loop is doing.
It is possible, if you fill that buffer in your game loop, that taking too long to get back to the game loop will result in the sound buffer being empty and a looping sound being heard. To avoid this, developers will either use a big buffer or fill the buffer from a background thread.
As you might guess, audio is already running at some sort of latency, proportional to the amount of data in the buffer that the game attempts to keep in there at all times. This is usually not so noticeable since sound takes a non-negligible time to travel in real life anyway. Pro audio applications have to keep this buffer small for low latency and responsiveness, but they don’t have graphical frames to worry about…
As far as input, yes, it is often affected. If a game does not decouple the rendering rate from the input handling rate, then there will be some additional latency on the way in. There will always be some additional perceived latency on the way out too, if you consider input latency as the length of time between performing an action and seeing it take effect. But that perceived latency may well be larger than the simulation latency, since the affected entity may have been altered at an earlier timestep than the one displayed in the next frame.