Bullzip PDF Studio combines PDF viewing, merging, and splitting into one simple solution.
There isn't anything complicated here; it is very straightforward with a functional UI that sticks to the specific task at hand. Bullzip PDF Studio supports viewing, searching, printing, merging, splitting, and rearranging PDF documents. During testing, it performed well without much lag even though it is a bit large compared to other similar products. It also places two desktop icons, one of which (merge) is included within the main program, so you can eliminate it if you prefer.
You can use it as your go-to PDF reader as well by simply selecting your document (or drag n' drop it in). From there, you can easily open, view, and print your PDF document(s).