Actually on Global ROM, this phone feel as capable and it can.
I actually only experience serious heat if I gaming on high 3D game, on other lower demanding activity actually barely feel any heat.
It actually perform no lag than other so called high end phone on long term usage, with installation full of apps and store photo inside the phone. ( My friend Samsung S5 and HTC M10 getting so much pronounce lag and heat, even only just install some basic chatting, casual game and social media apps only.) It just feel a bit slower on apps launching and navigation, but never to a lag state, where phone will hang for a while to perform something. Of course, all those thanks to the latest ROM, earlier ROM indeed lag.
The only minus are it’s screen color, unimpressive screen viewing angle, it’s average camera, it’s low speaker phone loudness, under average build quality, slow Micro SD read, and average battery life.
But other than that, it is perfectly usable, acceptable as just priced a fraction of those expensive phone.
A more worth upgrade will be Redmi Note 3 Pro 16GB version with Snapdragon 650, which improve almost all these shortcoming, and priced so not much expensive than this.