In Ilya Grigorik’s article regarding image optimization, he made several considerable suggestions on improving website performance.
Avoid Using Text within an Image – Avoid encoding text inside an image if at all possible. Opting for web fonts allows the text to be more user friendly. Unlike image text, web fonts will be selectable, searchable, zoomable, and high DPI-friendly.
Vector vs. Raster Images – Always use vector images if possible, as they are resolution independent and deliver sharp results.
Scaling Images is Optimal – Scaling images is the fastest way to reduce unnecessary pixels. Reducing an image to the display size is simple, and it is most optimal before making any other needed adjustments.