Lirc irsend interrupts music

I have set up my Raspberry Pi to send out infrared signal trough two ir leds using this guide:
I am sending out the following type of commands:

irsend SEND_ONCE NAD vol+

But whenever I do this the music interrupts for a fraction of a second. When I was doing some processor intensive task (like compiling some sources) this wasn’t an issue, only irsend would interrupt the music.
Somebody has an idea what could be the problem?