Earlier quoted context omitted.
You're overinflating your tires. A lower pressure will increase your speed and efficiency unless you're riding in a velodrome. Here's a video about this: https://www.youtube.com/watch?v=7r8f3w89XeM (watch out, there's a lot of extra stuff in this video about the machine they use to measure efficiency)
(Well, they should tell the manufacturers…) The video's result for both tires they tested was peak efficiency at 5 bar. They had a really coarse sampling of a whole bar, so that works out to a pressure of 65–80 psi.
The manufacturer rating is likely a max allowable pressure rating.