Streaming music falls out/stutters on the Mac since I have El Capitan

Since I have updated to El Capitan I have problems streaming my music from iTunes via Apple TV version 3. Sometimes it goes ok for minutes and than all of a sudden it starts stuttering or falls out. Than the music comes back again for a minute or so without stuttering and than a bit later it stutters again. This goes on and on. While it stutters it helps clicking random in iTunes to get a bit less stuttering or to get it back running when it was out.

But when you work at the computer while streaming music the stutting seems to be worse.

Music via the Mac speakers works without problems.

I have a Mac CTO 21,5" 5670/SD (ZOJM) from march 2011 There are no open updates at the moment of any software

The Apple TV is a 3th generation MD199NF/A from november 2012 update today to the latest software version.

I could not find any thing on internet regarding the stuttering in combination with El Captan. Does anybody have the same issue and/or a solution for this?