Garageband on macbook pro retina records out of rhythm

Hi all. I use a macbook pro retina 15" with a 2,4 GHz Intel core i7, 8 GB ram at 1600 MHz DDR3.

I have this problem: I'm recording a demo in multi-track with garage, so when I rec the guitars and the bass guitar without the voice and the drum (i record them one by one, not all together) all is ok, but when I'm recording drums and voice suddenly garageband starts lagging so it records out of rhythm. In other words when garageband plays guitars and drums (for example) while I'm recording the voice, suddenly it starts to play faster or slower so the track I record is out of rhythm.

I also tried to record the different tracks (guitars, bass....) in different projects (obviously at the same rhythm rate with metronome), but when i put that together all went out of rhythm again....

Please help meeeee 😮😮😮😮😮😮😮😮😮