I remember 3 years ago, when I was teaching a bunch of freshmen how to use Linux, the students had a rather unpleasant experience of having their computers freeze and become unresponsive. It was embarrassing since I was trying to sell Linux to them (as an alternative to their illegally acquired Windows OS). I immediately checked the culprit and it was one of popular PDF viewers bundled with the distribution. Unfortunately, the lab was not connected to the internet, so downloading an alternative viewer was out of the question. I had to make them abandon the exercise 'til the next session, hoping that those in charge of the lab will be able to install an alternative viewer. If you are looking for an alternative PDF viewer, outside of what comes bundled with your distribution, polishlinux.org has a short list of the more popular ones.
In the end, despite the size, we ended up using Adobe'sfor Linux. At least we're sure that it comes from whoever defined the PDF standard.
And oh, just in case you're wondering what happened to my class, everyone passed but I doubt if anyone took Windows out of their computers and installed Linux. :(