Animation Speed

I work with mobile phones but not on games, so I won't comment on that. One thing I can think of that could use over 100 is bullets or something.

Okay, as I suspected, real FPS loss is a factor here. In for example, when running a game around 20-30 FPS, it's not unusual for there to be large, quick dips in the FPS. When running the game at 1-5 FPS, there can be skips as large as 30 pixels.

When setting to fixed rate 30, the frame rate isn't likely to drop like this, since you probably have more than enough power to maintain a consistent frame rate. But in the real world, dips like this can cause huge discrepancies.

So with a 'fixed' delta time, this isn't an issue and you can set a the frame rate and set minimal speeds and ignore sudden dips.

As for high speed objects, I doubt that'll be a problem, as long as the frame rate/delta time stays consistence.

In the example file I posted previously I can't reproduce any increasing inaccuracy with low framerates. As I mentioned in the post, even at 2 FPS it usually lands within a pixel of its target.

Going back to my point about pixel precision of fast moving objects as Jeswen mentioned - I don't think it matters that much if a bullet is a few pixels out. You'd never be able to spot the difference. I understand it's a problem if you need pixel perfect platform movements, but I was suggesting that platform movements would tend to be at low speeds, so still having a high accuracy.

I tested it on 4 computers and 2 fixed frames. Two out a range of 100, the other two were more reluctent to make large jumps and put out about 50 eventually. 2 laptops, and 2 desktops. So it seems to vary between systems to an extent but most will probably be capable of producing these anomolies when struck with low FPS.

Granted with the time delta override this is all a moot point.