This is your reminder to wash your Kamek if you have been using it for a couple of months now. The speed is going to change as the pad gets used by you this is the same with every other mouse pad. The Kamek is water and soap friendly due to the weave and washing it will definitely bring back noticable speed.
Next time you know you will be gone for the day spend 15 minutes washing it and leave it to dry for when you are home again!