Just built our first major react/redux site. Moderate complexity, I'd say. React runs pretty fast, but on page load we take 2.5s to compile all the JavaScript.
In a large application my rule of thumb is 1/3 compile, 1/3 React internals (which includes DOM updates) and 1/3 product code. 2.5 seconds is a lot, but not surprising if an application is being shipped as a multi-megabyte bundle.
Compiling as a build step doesn't get you very far when you are forced to ship source code to JS engines.
I guess I may be a bit confused on what he meant by compilation
Since JS is JIT compiled, I assumed perhaps he was delivering his scripts in raw JSX+ES6 and transpiling at runtime via babel's browser.js (as shown by react's Getting Started guide) [1].
If he meant time spent parsing the JS then I'd be a bit suspicious about the 2.5s both because of the extraordinary length and also I find it hard to believe someone who would know how to measure parse time would mistake the term with compilation.
