[iainmerrick]

I wouldn’t necessarily write this off. Doing UI-related work directly in the main thread has a lot of benefits -- your click listeners can take effect immediately and make all the necessary UI updates before the next event is processed. With event handling in a separate thread, it can be harder to make things robust (filtering out double taps, preventing flashes of unfinished/unstyled content, etc).

Of course you do need to make sure that everything that could be even slightly expensive is shipped out to a background thread. JS is weak in that respect.

Moving everything to a background thread does fix that problem, but I think it’s overkill. A lot of mobile apps would be faster and more responsive if they used the main thread more. You just have to use it right.