I'm encountering the same issue.
I've got two Pi's setup around the house to control my TVs from my iPhone, Pi B and Pi B+. (Loosely based on slimjim777's awesome web-irsend project: https://github.com/slimjim777/web-irsend
Setup a third one based upon a Pi 2 and IR transmission doesn't work correctly.
From scratch install with NOOBS v1.4 and all updates (as of 2015/03/15).
Looking at the IR output on my scope and the transmission looks like what Elmicha posted. Pulses are spaced way too far apart.
The total transmission time for a code is around 500ms instead of around 50ms.
B+ that works: 3.18.7+ #755 PREEMPT Thu Feb 12 17:14:31 GMT 2015 armv6l GNU/Linux
Pi 2 that fails: 3.18.7-v7+ #755 SMP PREEMPT Thu Feb 12 17:20:48 GMT 2015 armv7l GNU/Linux