do laser diodes loose efficiency after a while?

hi, i made a typical M140 445nm 2w handheld laser powered by a mohgasm 1.8a driver.
for some reason the burning power of the laser seems to be weakening.
I know its not the batteries, because I have been using a steady power supply from time to time, and i notice a difference.

It could also be a problem with the lens, as i am seeing much more blue speckles all around the focused beam when it hits a wall. Although im not sure how to clean it. I have tried.

These laser diodes are not designed to be run at such high powers CW, they are pulsed in their original applications. Thus, over time, the diodes will degrade from being overdriven, and there isn't really anything you can do about it except turn down the power, or replace the diode.