A ton of RAM being used with nothing open
I see dozens (if not hundreds) of programs open. You may only have three that you are actively using, but there are dozens running in the background doing all sorts of things from indexing for Spotlight to watching for new software updates.

RAM being used is not a bad thing, especially when you have so much free (per your screenshot). You paid for it as part of your computer; why wouldn't you want to use it?

Apple's support article states that unless the graph to the left is showing red (or, to a lesser degree, yellow) that you have absolutely nothing to worry about.

Given that your RAM usage is not particularly high, the sluggishness is likely coming from elsewhere. Even if you just look at pure numbers (which is absolutely not the way to read RAM information), you still have over a gigabyte of free RAM and zero swap-file usage.