Nice website! Some unsolicited advice: Just looking at the switches page of your website, most images are around 100 kb despite being visually fairly simple. Naively saving one as an indexed PNG image resulted in no visual changes but reduced the size by a factor of roughly 2. I would recommend optimizing your images in addition to what you're already doing if loading time is important. SVG probably would do even better, but I don't know how you're making the images, so I don't know how much work that would be.
