Sometimes you can experience that the playback when starting up the engines , the playback seems to have problems.
Just start up the ZooKeeper and it will disappear. If in programming mode or live mode the choice of "fading" between layers it can be wise to
plan , what content you are going to have in your timeline. Otherwise the memory of the card will be stretched to it´s limit.
f you play HD clips on layer 1-4. then want to play HD clips on 5-8. you will need to play a SD pal clip or lower to release the video memory
it preserves video memory from the last video played.To release the video memory you need to load a smaller video clip.
You may experince staggering loading of clips.
If you create a timeline playing one clip on layer 8. If you load 7 clips at the same time on layer 1-7.
You will see the output hick. Especially if you load 4 HD clips at the same time.

A easy work around is to staged the loading of the clips. And preload the clips before bringing the level up of the output.

As always, the machine is not brighter then you, but can be as stupid as you if your not aware.
Always remember that the machine is not your brain, it is a stupid box that can perform powerful things only!