Excellent in-depth analysis on getting pages to start-up faster from Addy Osmani, a Google Chrome engineer. The whole thing is deep and worth reading. This part especially struck me:
Every few years, it’s proposed engines offer a way to precompile scripts so we don’t waste time parsing or compiling code pops up. The idea is if instead, a build-time or server-side tool can just generate bytecode, we’d see a large win on start-up time. My opinion is shipping bytecode can increase your load-time (it’s larger) and you would likely need to sign the code and process it for security. V8’s position is for now we think exploring avoiding reparsing internally will help see a decent enough boost that precompilation may not offer too much more, but are always open to discussing ideas that can lead to faster startup times. That said, V8 are exploring being more aggressive at compiling and code-caching scripts when you update a site in a Service Worker and we hope to see some wins with this work.