You may want to try limiting frame rate in GZDoom:
1. Run the level in GZDoom, and press the ` key to open the console. (The ` key is located above Tab on your keyboard).
2. Type vid_maxfps 60 and press Enter. This will limit the game to 60 frames per second.
3. Press ` again to close the console.
Alternatively, you can also set cl_capfps true in the console which might help your issue: