Hi Martin,
Unfortunately Compare plugin takes A LOT OF TIME comparing some kind of files (that is because of their content, not their type). I suppose your files are falling in that group.
It also doesn’t show a meaningful progress in that case because the compare process is not linear and there are several compare stages. Your comparison is having troubles in the early stages (because of the file contents specifics) but it is very possible once that stage is over the other stages to go almost instantly.
I’m pretty sure it is still comparing, it hasn’t crashed but there is no way to check how much time it will take it to finish.
Having said that leads to the conclusion that Compare plugin is pretty useless in your case.
You’ll need to kill the running Notepad++ instance from the Windows Task Manager because the progress Cancel button won’t work in that situation.
I suppose it’s not the case but if it happens that your files are not confidential I’ll appreciate it if you send them to me so I can further check what’s happening.
BR