If I create a new empty project and export it with all minification/recompression options enabled, the result is just 210kb zipped. This is a very small overhead compared to many other tools (some of which have several megabytes overhead).
Adding plugins and behaviors will slightly increase that, but their script sizes are usually pretty small. If I add Sprite, Platform behavior and Solid behavior to the empty project and export again, it increases to 220kb - it only added 10kb.
Most of the rest will be the content of your project, which is in your hands!