Attention smartphone nerds — the new HTC One (M8) includes the option to use the experimental, pre-release ART runtime should you desire to make that switch. Android 4.4 introduced the new ART runtime — an alternative to the standard Dalvik runtime intended to let developers and OEMs get to grips with the new code before it becomes the default. But so far it hasn't been available on all KitKat devices. The old HTC One (M7) for instance didn't get ART in its KitKat update.
Like to live dangerously with preproduction runtimes? HTC's M8 lets you do that.
On phones where it's available, such as the Nexus 5 and Moto X, some regular users and tinkerers have switched to ART full-time, as it seems to bring a small but noticeable boost in responsiveness. As ART is still in the experimental stage, however, that extra performance comes at the cost of compatibility with certain apps. Nevertheless, if you understand the risks you can enable ART on HTC's 2014 flagship from within the developer settings menu as usual. (Whether you really should is debatable, but in any case, the option's there.)