If your current export is, say, 100MB, it will only significantly grow in size if you add more assets to the project - images, sounds, big files. Other things like the amount of code, plugins used etc. are negligible.
Oh... this is scary, I just had a conversation with one of my colleagues, I showed him my work in progress and he was defiantly surprised from it (consider it's not finished yet).
After he played with it a bit I brought up the compile subject and he suggested to export it using native .exe I explained to him that I'm using a game engine called "Construct 3" and there is no such option and the closest thing is using NW.js (after he done laughing at me) he explained to me that by using NW.js my project will become HUGE! which means also slower loading times and download, and it's not efficient in code since it's based on a browser wrapper etc.. and many other details I honestly don't understand as I'm not a programmer and he know that so he tried to explain it "slowly"...
After I explained to him that C3 is my current choice since I'm NOT a programmer (and he knows that) he still insist that I'm wasting my time working on my current project with such limited game engine which he never heard about before he was surprised how come it can't even export to native exe file which is industry standard for years and it will remain for many future years ahead with all the respect to HTML5 and so on blah blah blah (technical things that I can't even follow here).
At the end, he suggested to either wait for the game engine I'm using (C3 obviously!) will add this basic feature unless they have reasons to not do so (probably true) the other options are to port my project to either pure code or based on a game engine that actually supports native .exe which will be MUCH more efficient and size wise. (EASY for him to say) as he's a very experience programmer and I'm NOT! ;)
After few tests I'm afraid he was correct as I didn't even start importing my assets (which will defiantly make the project bigger) it's already around 120 MB ! (for Windows OS) and it's pure UI which doesn't make any justify to the size of the build and I don't see any info yet about NW.js getting smaller or change in size for other OS... this is sure bad news for me.
Unfortunately, as for now I have no choice but to use C3 and NW.js but these facts totally discouraged me to be honest... for now I'll probably keep working on this project using C3 because porting it is something else will cost extra $$$ that I cannot afford anyway at this time.
With all the discouraging vibes... I still LOVE C3 I think it's a good start to learn how to program basic things, and I love learning new things every day I ran into an issue, so back to work! :)