jetpack-photon-for-nextgen-gallery

Great concept, but I would not recommend installing. Plug-in does nothing (does not work at all) plus it apparently has been abandoned, as there have been no updates in over a year.

not working any more. it's a crap

Seems easy. Installs easy, doesn't conflict with anything. But, I can't find out if images load faster. The Pingdom score doesn't show the site to be faster. So, I'll keep testing it, for now it is a 4 but could easily be a five once I verify that it is working. I have 2000 images in NextGen galleries and I hope they are loading faster.