Blog
Technical notes on what I'm breaking and fixing: reverse engineering, internals, weird bugs and vulnerabilities.
In GTA V the same car hits a higher top speed at higher frame rates. An Adder does about 185 km/h at 30 FPS and 227 at 350 on a flat straight road, same car, same input. Turns out the tyre model integrates on the render clock, so how often it runs (and the car's top speed) rides your FPS. Here's how I traced it and fixed it.
A years-old GTA V performance issue, FPS tanking at night when looking at the city, traced to six prefetchnta hints into write-combine vertex buffers, stalling the AMD Zen pipeline. The final fix is 25 NOPs in two places.
VR players' grabbed items appeared floating away from their hands on remote clients. The fix was a single mov instruction in the IL2CPP-compiled DLL.