[instantk]

My lumia 640 came with double tap to wake enabled by default. The touch settings, where thia feature is present doesnt show any warning that it would consume higher battery as my lumia 520 used to show.. Also.. The glance screen which gets automatically activated each time i put my phone out of pocket makes me feel that the screen of the phone keeps awake even during no display... So anyone here noticed significant difference in battery life keeping this featured enabled on new lumias?

[RumoredNow]

The features (DTtW & Glance) are holding some low level functionality open on your screen until activated into performing actions. There is no denying it. But it is the actions that do the battery consumption to any significant degree.

That said the SoC in your 640 is way more efficient than previous generations.

I like the functionality and always leave them enabled. To me it is worth any tradeoff (minimal, IMHO) in battery endurance. YMMV.

[noersetiawan]

My Lumia 520 doesn't show any battery warning either. No need to worry, battery drain is really low on any phone (even Android) for that feature, apparently screen digitizer uses very little power to keep active, and it doesn't even active all the time, when the proximity sensor is covered up (as when the phone is in your pocket or put facing downward on a table), it goes off and not receiving input. The same goes for glance screen, it won't turns on when the phone detects that it is in your pocket.

[RumoredNow]

The same goes for glance screen, it won't turns on when the phone detects that it is in your pocket.

'S'right. I don't want Glance seein' wot I got in my nasty pocketses.