Most people don't seem to grasp that in this day and age, any GUI program (at least on OS X) is going to be minimum 20MB due to the retina display. Add in that realistically you need to use Webkit (or some HTML renderer), at which point... 100MB is pretty good.
For reference, an RSS reader I threw together using standard Cocoa widgets will hit 50-60MB with no issues, and that's with my being annoyingly judicious with how it's built.
For reference, an RSS reader I threw together using standard Cocoa widgets will hit 50-60MB with no issues, and that's with my being annoyingly judicious with how it's built.