Sorry for the delay! I just uploaded the file.
When attempting to recreate it to reconfirm the steps - I managed to confirm that it does have something to do with autosaving, possibly while the syntax coloring is active. I couldn't seem to reproduce it while just navigating the file but I added a space to an empty line to trigger the autosave and was able to trigger it. This time, though, SE didn't lock up and I was able to copy/paste the entire stack into a text file and uploaded that along with the screenshot, the offending file and the workspace tag file (775 mb alone!)