I think the best way to optimize icons is to save your svg’s in a spritesheet, include that spritesheet by default on all pages (hidden of course) and use references to it when you need an icon.
Sacha created a build plugin for that particular reason more than a year ago, I haven’t used it in a while, but it should work or at least with a few tweaks here and there: Compiling SVGs with the Build Plugins API