I'm new here and started to play OpenTTD and noticed some minor issue. The window drag didn't feel smooth so I decided to look into it. I've done something like this on OpenRCT2 before where GetTickCount's resolution simply isn't precise enough.
So I've basically replaced the GetTickCount function with an alternative where we get 1ms resolution, this ensures the game also runs at exactly 33 ticks. I also moved the window update out of the game logic loop so it will get redrawn every iteration.
Heres also a comparison video:
Edit: I shall mention that GetHPFLocalTime is planned for another patch I know that it is currently unreferenced.