I use Speeder on Windows 11 (along with many others, I'm sure) and have never experienced a crash, though I am aware some people do experience crashing/closing. One person mentioned that the "crash" did not appear in Event Viewer, which makes me think that some people on Windows 11 have something on their PC that is closing the program. One way to close the program is by sending an escape keypress to the Speeder GUI. I have now disabled this method in hopes of solving the issue, but I would be surprised if this were the solution.
This requires updating Speeder to the newest version.