Honestly, the stress originates from both. There was a lot of pressure to work ridiculous hours during the week and come in during the weekends (wtf??)
On top of that, the tools sucked. They give you a shitty laptop (frugality) that would go to the "locked" screen after x minutes if you were idle, and logging in could take 10 minutes because it was attached to an AD network and sometimes decided to use the server in China for authentication (seriously?) If your keyboard broke or something of the sort you had to wait in line for hours to get another (crappy) working one. They force you to use homegrown tools and plugins that are crashy and frustrating. I was soo tempted to just spend all the time fixing the tools, but I'm sure that would have gotten me into trouble, though it would have probably improved every software engineer's productivity. This was a few years ago. Maybe someone has fixed all this by now :)