You've probably noticed that Acrobat Reader is not the quickest application to launch. As Adobe has piled on the features over the years, load and viewing times have increased as well. That's troublesome for those who simply want PDF files to open as quickly as possible so that the content can be viewed.
There are a couple of routes that you can take to speeding things up. First, there's a free application called Adobe Reader SpeedUp that's widely available on the Internet. One reason Adobe Reader is so slow to start up is that it utilises a lot of plug-ins by default. These plug-ins (small applications that add functionality) are useless to most people but do add some functionality. Adobe Reader SpeedUp can disable those plug-ins, thereby leaving you with just the reader.
Another route you can take is to ditch the Adobe Reader application altogether and use an alternative. Although the PDF file format was created by Adobe, plenty of Reader knock-offs now exist and some of these have grown popular, largely because they're fast. One of the most popular is Foxit Reader. Boasting small size and quick startup times, Foxit runs under all current versions of Windows and supports most of the functionality that the full-blown Adobe Reader does. It's worth a try.