Mediatek is the lower end brand of CPU that powers much of the world's smartphones. Many of the Chinese phones include a Mediatek chip set. In the past I have had trouble with Mediatek performance, but recently things have really gotten better. In some devices the Mediatek chips actually perform well.
Stagefright was the crazy bug a while back that effected about 99% of all Android users. The bug allowed attackers to gain complete access to your phone if you clicked a media file sent by the attacker which included the bug. While most flagships patched the bug quickly, Mediatek handsets have remained vulnerable.
Yesterday "BlueFlame4" posted several recovery flashable zips that fix Stagefright on devices with a Mediatek MT6753 chip. Devices like the Elephone P8000 were fixed.
via XDA