Is Bluetooth (headphones) efficient for gaming?

Searching around, they should be fine if you get some specific things. Mainly, it means getting aptx codec, preferably a headset with the latest bluetooth version (4.2 right now if I'm not mistaken) or that provide low latency and a adapter/dongle that has low latency (< 32 ms).

From to this reddit thread:

you need APT-X to get rid of latency over bluetooth, otherwise it's completely unacceptable for absolutely everything imaginable

and

What you need is a BT 4.0 with low latency headset and a matching transmitter with also low latency feature. BT chip behave this way for the extra feature(APTX and Latency) to work both the receiver and transmitter must have the feature.

Here's a good article on bluetooth headset