D’oh. Sorry, I mixed up my workstations (there is a good reason that servers have names). I edited my previous posts to have the correct numbers.
So, WS1 is indeed slower than WS2 for both Matlab and Julia. I was getting the impression that WS1 is faster because by default Matlab is multi-threaded (and WS1 has more cores). Mystery solved. Thanks a ton @tkoolen!