AAC Bluetooth Codec causing too much CPU load?

Hey guys,

I am using the upstream 2.1 diy board
my project
After the last firmware update the bluetooth playback has become a little weak.
Especially the hihats in electronic music sounds a little different at every beat. Once or twice in a song there’s a little timing offset too.

I figured out that it’s well playing when set the bluetooth codec to SBC manually.

Could it be that new functions like web interface limit the AAC decoding ?