Chassis requirements for WP8...dual core mandatory.

[Heron_Kusanagi]

Minimum hardware requirements for Windows Phone 8 revealed | WMPoweruser

At least this means multitasking should be fine.

 

[Munkeyphyst]

This would explain the continued release of 7.5 devices. The older single core chips have to be significantly cheaper.

 

[AngryNil]

Also seems to make it the easiest platform to develop for. iOS does have some legacy hardware that can be a pain to support and Android is a total crapshoot.