Agreed, Turbo FF would be a good addition.
Implementation idea: a hotkey would switch Turbo mode on, then the FF button/hotkey would trigger the faster speed instead of the normal FF speed. The button graphic could change to 3 forwards-arrows >>> instead of 2 >> to indicate that Turbo mode is active.
Some concerns: FF speed is sometimes inhibited by graphics rendering. Switching off HQ minimap fixes this, for the most part, so maybe Turbo mode would have to deactivate the HQ minimap to be noticeably faster. Not sure if this is possible to actually do in-game, but I guess we can find out.
Another approach would be to have Turbo mode move the game forward at a certain speed regardless of rendering needs, which would make the speed always the same, but would result in frame-dropping/forwards-skipping, depending on how heavy the rendering load is. This would be a lot more work to implement, but I'm looking at this approach as a possibile solution for the upcoming Superlemming speed anyway, so it's worth taking the time to investigate it.
Incidentally, Rewind has actually been slowed down a touch for the next update, because I wanted to mitigate panel glitching. Using a TTimer to handle the skips achieves this, but the skips have to be less frequent to prevent other time-related bugs. It's still fast, but is now slightly slower than the current FF speed.
