I can't speak to that specific model, but when I've seen a CPU fan fail on other appliances the CPU severely downclocks itself to keep from overheating. This causes everything to be unbearably slow including just typing characters in an SSH session. The first time I encountered this it took me quite awhile to figure out what was wrong (it was stumping TAC as well) which is why I mentioned it in my book.
Attend my 60-minute "Be your Own TAC: Part Deux" Presentation
Exclusively at CPX 2025 Las Vegas Tuesday Feb 25th @ 1:00pm