Oh wow :/ Okay. Well devs say that Audiotool works best with Google Chrome. You might want to email audiotool staff about that! Perhaps those PCs don't have enough RAM to even handle the program, or it's internet connection. When you go to use it, in the app you will see an Activity % in the bottom right hand corner. When you open the app on one computer and add just a loop or something really small and click play, what is the percentage? Lag can be a result of you needing to delete cookies, history, or RAM space, browser cache/cookies ect. My best advice is clean as much as you can from browser ! Sorry about the inconvenience man! Try talking to Devs directly!
I am user TopHat/jace. by the way ! (: