heavy Rated 5 out of 5 stars

829k seems a bit heavy compared to other reminder type extensions (~22k). It seems you have a calerndar-y mindset. Thought about tossing code at the mozilla sunbird project?

This review is for a previous version of the add-on (1.9.6). 

heaviness

A lot of that is attributed to a number of icons used for toolbars and UI elements, etc. But a larger part is just the evolution of a 5-year piece of software, as new features continue to get added. Check the View Past Versions link to see a history of the versions and their associated size.