Adobe Reader was, for a long time, the only way to view documents created in Adobe’s Portable Document Format. Over time other software emerged to allow users to view these documents but the most “lightweight” example I’ve seen is Sumatra PDF reader.
Although not feature-packed, Sumatra PDF is blazingly fast and useful enough to do the job. It makes you wonder why Adobe Reader is so “heavy” for what it is. Just a PDF document reader.
Try it out. I’m sure you’ll be pleasantly surprised.