You don't need to resize the files. Just convert them to PNG.
JPG is an awful file format for black and white images. If you convert them to black&white PNGs it will massively reduce the filesize with no loss in image quality.
Example: 006.jpg is 16.9mb
Converted to PNG, 006.png is 6.2mb.
The image data is exactly the same, at about a third of the filesize.
@qazmlpok Thank you. I typically leave the setting to "auto" when converting with Honeyview. I don't have the sharpest eye for minute bits of quality but I'll try to remember this for next time.