It does sound a bit odd that you're frequently running out of application memory and having to quit Finder. This isn't a typical issue, especially since Finder is a core part of macOS and generally runs smoothly.
First things first, it's important to check how much RAM your Mac has and how it's being used. You can do this by opening the Activity Monitor (found in Applications > Utilities). Here, you'll be able to see if a specific app is consuming an unusually high amount of memory.