Well, that's 300k of gzipped code, so while the bandwidth isn't huge (300k is barely a large image these days), that's a ton of code to be parsed, and might be too much of a CPU hit for anything mobile.
Oh, my comment wasn't at all clear, but I was talking about inclusion on web pages, where you'd be flicking forward and back between them. In which case even 50ms on top of the rest of a page load would be hurting you.
I'm sure it's fine for a SPA, and for a mobile app it's a total non issue. Actually I'm planning to use it for one with React Native myself.
Luckily, people will probably not be including the full compiler lightly; I just wanted to point out that it's not as cheap as a jpg of the same size would be, an impression I thought the parent comment was giving.
You'd probably not want to use this on websites, unless you want to be able to compile code directly in the browser, such as when you're making an interactive tutorial or similar. Otherwise, you're better off with stripping out all of those parts.
There are a lot of commonly used mobile libraries that are larger than this. Some of them (e.g., JQuery Mobile, which weighs in at several megs) make this look tiny by comparison.
Not that 300K should be considered a huge amount by today's standards anyway.