the change to SVG is only applied to the free theme icons, so the premium plugin icons are still to be updated, which will be coming in one of the next updates.
We’re working on GPP 1.9 right now – it’s a big feature release, which is why it’s taking so long.
That being said, a 2kb file should not be taking 400ms to load. That sounds like there’s something wrong with your server, or the testing tool you’re using.