I'm using Scapple (https://www.literatureandlatte.com/scapple/overview) as a way of learning and jotting down information to link ideas; and sometimes to even give presentations. I often take screen shots (just a fast, effective way for gathering information), and I'm finding that these files are becoming enormous. Not only does my Mac then become slow, but the files become very large. This file came out to be 167mb:

I wouldn't care if the screen shots are of poor quality. I've tried a couple things (https://about.gitlab.com/blog/2020/01/30/simple-trick-for-smaller-screenshots/); I've also changed screenshots from png to gif in terminal (defaults write com.apple.screencapture type gif), but it seems that these aren't really working for screen shots that are being clipped and then pasted. This mock file, for instance, has four screen shots and is 24.7mb. I really want these files to be as small as possible, while still being readable with some color.

Does anyone have tips or experience in reducing the file size for this app on macOS?