cider is consistently crashing emacs when I accidentally build an infinite loop. C-C C-C does nothing to cease execution. How can I stop crashing emacs? Is there a way to break out of long running loops? Or reliably terminate execution without killing emacs?

Are you doing C-c C-c in the REPL?

some repro steps of your problem would help troubleshoot it

Try C-c C-b instead.