Windows task manager...how many "processes" is it normal for my computer to be running when I only have one program open?

Lately my computer is always “thinking,” and really slow to respond to any command. I opened my Task Manager and under the Processes tab see that there are currently 55 Processes going on. Examples include Host Process for Windows Service and Task Scheduler Engine. I’m sure some of these are completely valid, but what can I do to make my computer run more quickly/smoothly? It’s getting annoying. Thank you.