> Edit; Okay i know i could buy a bigger data pen, but i also do weekly backups to the cloud and am limited to 7mbps upload, 2g takes 40 minutes, so every bit i can shave off helps. But i want to emphasize i realize it won't be important for the majority of users

Curious here: so you continuously upload your Thunderbird executable to the cloud? Why? Most upload+sync solutions worth their salt (FreeFileSync, Syncthing) have competent diffing algorithms that don't upload the same file twice.