Autorun programs are set to boot whenever your operating system boots. They all try to start at the same time. Eventually, you end up with a huge logjam of activity as each program vies for processing power.
But you don't need to start these programs at the same time. In fact, some of them you might not use at all! You should be running most of your software only when you're using it.
Unfortunately, tracking down autorun programs and preventing them from turning on automatically isn't the easiest thing to do in Windows.
That's why there's Autoruns. It's a free program that tells you every program set to run at startup and the start order. You can easily disable ones you don't need.
To use the program, just download Autoruns, extract the file to your hard drive and run it - no installation necessary. You can extract all files or you can just extract Autoruns.