Hi All, I’ve come here from Open question - Using the Imgur plugin, how secure is it, into the future?, thanks to @Olondre for directing me here 
I use ShareX - The best free and open source screenshot tool for Windows
You can set it to save in .jpg, and set the compression level to your preference
(I’ve been uploading my non-sensitive images to Imgur for the past year, and have now decided it has to stop, so what now, I enjoy visually interesting notes)
Exactly what I was thinking, after having used it extensively for a year!
This is what I’m now considering.
Anyhow, hope this helps with image compression 