I think that SVG is best done with a 'stylesheet' of SVG definitions that then get 'used' with the use tag in inline SVG. So you make one rectangle and call it something sensible. For icons and other mono elements the 'currentColor' feature is great as that will pull your colour from whatever else is in the div that contains that particular inline SVG, e.g. a 'a' link can surround the inline SVG and get coloured accordingly.
Taking the 'SVG stylesheet' approach means that the actual SVG can be generated, so it can take variables in the backend code, e.g. to localise the icons/images. This can then be ajax loaded into the DOM in such a way that all the SVG images are only loaded once in one reasonably optimised but editable file. Subsequent pageloads will be fine, no need for all of those http requests.
I use SVGO a lot but I think there is a lot to be said for using 'rect' instead of a path.
For some reason I decided to re-do the 18Mb Adobe file that was 'vector' that Instagram have as their definitive icon. I got this down to four lines of SVG, with the result being accurate rather than yet another kid-with-photoshop-redesign effort. Had I taken the 'let's gzip it morely' approach then I would still be waiting for my icon to download.