Yeah, basically this. I found this post, where back in 2012 some guy tested the maximum file size for text files in a browser, and he didn't start hitting problems until around 35 MB. The only game I'm aware of that's had file size problems was the final release of "Stranded", which was 83 MB (mostly due to embedded images). So you're nowhere near a problematic size.
As for your widget, I also agree that if you're at thousands lines of code for a single widget, then you're doing something wrong, or at the very least, dangerous.
So, your HTML file size is nowhere big enough to be an issue yet, but you really want to avoid putting too much strain on any single widget, macro, or function, otherwise it's going to be messy when something goes wrong.
Hope that helps and I enjoy your game! :-)