SVGO is an easy-to-use tool for optimising SVG files, cutting size by up to 80% without affecting image quality.
The program has just about as minimal an interface as you can imagine. It opens with a window and a prompt to drag and drop your target SVG files; when you do that, it compresses them and displays how much space you've saved. That's it. No menus, no buttons, no dialog boxes, no configuration options, nothing else at all.
One problem with this design is it means SVGO will overwrite your source files and there's nothing you can do about it.
Let's repeat that for emphasis. SVGO will overwrite your source files and there's nothing you can do about it. Always work with copies.
Use the program correctly, though, and it works very well, effortlessly stripping out redundant SVG data without affecting the final image.
SVGO couldn't be any easier to use, and it really can achieve some good compression rates. Be aware that it overwrites your source files, though, and the program doesn't always work as well as SVG Cleaner - be sure to try that as well.