1) Start PerfStudio client
2) Connect it to GSDumpGUI.exe
3) Set the working dir folder in the two top-right boxes
4) Press start (sometimes twice for rendering to start)
5) Choose the right window PID in the PerfStudio API selection window
6) Pause the process and open Frame Profiler
For some reason, GPU PerfStudio shows cpu/gpu times incompatible with those the program actually had before pausing.