One thing I'll never understand from players that HAVE TO GO FAST here is that nobody seems to know you can literally skip every mob in that underground tunnel section if you just walk. Yarzons and those spirits all aggro based on "sound" so they'll ignore you if you're walking slowly (although I think they do aggro if you walk right in front of their face).
I've also skipped the first group of mobs before, too. You can get around them and down into the rooms pretty easily.