OP really focused on payload size, is why I was curious.
> On a clean page load [of nextcloud], you will be downloading about 15-20 MB of Javascript, which does compress down to about 4-5 MB in transit, but that is still a huge amount of Javascript. For context, I consider 1 MB of Javascript to be on the heavy side for a web page/app.
> …Yes, that Javascript will be cached in the browser for a while, but you will still be executing all of that on each visit to your Nextcloud instance, and that will take a long time due to the sheer amount of code your browser now has to execute on the page.
While Nextcloud may have a ~60% bigger JS payload, sounds like perhaps that could have been a bit of a misdirection/misdiagnosis, and it's really about performance characteristics of the JS rather than strictly payload size or number of lines of code executed.
On a Google Doc load chosen by whatever my browser location bar autocompleted, I get around twenty JS files, the two biggest are 1MB and 2MB compressed.
Yeah, without a deeper understanding it's really hard to say... just the surface level look, I'm not really at all interested in diving deeper myself. I'd like to like it... I tried out a test install a couple times but just felt it was clunky. Having a surface glance at the org and a couple of the projects, it doesn't surprise me that it felt that way.