Startup time

[roman01la]

On my Xiaomi Redmi Note 5 it takes ~4 seconds till the app becomes responsive. After quick profiling I can see that most of the time is spent on evaluating JavaScript in V8. Not that it's terrible amount of time, but if possible I'd like to improve this.

Possible solutions:

• Move V8 into background thread, so UI is responsive immediately
• Compile V8 with startup snapshotting enabled
• Build the whole thing together and AOT compile with Prepack (requires additional type hinting on compiled code, doesn't worth to invest time)

[roman01la]

Moved V8 into separate thread, now UI and prompt popups up immediately, Eval button is being kept disabled till REPL initialization is done c3be0e5