WP dramatically bloating website size

This is one thing I cannot figure out the logic behind. I built a site for a client, an artist. It is fairly basic with various plugins, and does have about ten gallery pages with images. These images are not huge, maybe 1400px max in either direction. If you put all the images in a folder, it would be probably 30-40mb.

I began making a backup, and the site is now apparently 838mb. You read that right. 838 megabytes.

The backup hangs, takes forever or simply cannot execute, I let it run for 25 minutes and it was still “generating backup”. Let alone email or download with any efficiency.

I know WP creates different sizes and crops of some images for future use in some way on the site. But 838mb from a simple gallery website?

Is there a plugin or some way to go through and slim this down a bit? Remove unused images? I’m baffled.