[georgemcbay]

Many in-game interfaces are powered by Flash/ActionScript, running in things like Scaleform or various open source offshoots of gameswf but they aren't running in Adobe's actual Flash virtual machine, so any performance comparisons are pretty moot.

In any case, anyone who didn't build websites in Flash because it was "slow" was misinformed. Flash/AS, especially with AS3/AVM2 was significantly faster than JavaScript (at the time Flash was relevant) if doing anything that required "Web App" style functionality, at least if the ActionScript code was written by an actual programmer and not a designer copy-pasta-ing scripts to make something work. There are/were very valid arguments against Flash (security, un-indexability, etc), but performance compared to JS wasn't really one of them.

Source: used to write ActionScript apps that ran on the 350 mhz i.MX21 ARM chumby device with 64 megabytes of memory that had better performance than a lot of "native" mobile apps have today, let alone web-based mobile apps.