I have a OnePlus One. It's faster,
By my understanding of the technical specifications, that OnePlus One has a 2.5 ghz quad core processor which is shared between graphics operations and general purpose calculations.
But the A8 on the iPhone has a dedicated quad core package for graphics, and a dedicated 1.4 ghz dual core package for general calculations. I would guess that in general usage the iPhone is snappier and more responsive which some might consider "faster".
I have an iPad 3rd generation (dual core 1 ghz with quad core graphics) and a Kindle Fire HD 6 (quad core 1.5 ghz, similar chip as the OnePlus One I think). The old iPad seems like an order of magnitude more responsive and is actually usable for general purposes like email, websites, videos and games. The Fire HD6 stutters on things as basic as the keyboard and browsing but that could be the OS, handles Amazon videos well (not YouTube so much) and the games work although Hearthstone is noticeably slower than the iPad even though the HD 6 has a few less pixels to push.
I'd be wary of predicting performance based on clockspeed alone and so far in my experience the idevices are far more powerful than their budget Android alternatives.