This whole issue is not a latency problem. Logic 9 with plenty fast macbook pro, motu traveller etc.
The tracks don't start immediately on hitting play in playback because the mainstage clock is mid-bar so it waits until the first beat of the bar so that everything is in sync.
If you need a track to start immediately with nothing else you have to set it to play using play action (in the menu in playback) and make your play button a play button from the action menu not the play button for playback.
I wanted to make playback my backing tracks player and insert markers in Logic and transfer them across to Playback. 2 things happened - I couldn't get the markers to line up (even visibly dropping out of sync!!) in playback and it wouldn't navigate them without delay (a noticeable momentary pause) in playback.
The resolution for this after trying everything happened to be something strange in the bounce function in logic. When you select the bars it will accept and insert silence if your song starts at bar 2 and you export from bar 1. However, if you select outside the region at the end it on an even bar it doesn't like this at all. You must end it on an even bar within the actual region so this might mean inserting silence in logic to meet with an even bar or give yourself much more than you need then say if your region now ends at bar 81 try exporting/bouncing bar 1 to bar 80 and this should work. If your track ends at say 80.1.2.117 you will have to insert silence or record a couple of bars on the end to give yourself some wiggle room. Why it will give you the start bar in silence and not what you select on the end I don't know - seems highly illogical ;0D
If you try to bounce from say bar 1 - your audio starts at bar 2 and ends at 80.1.2.117 or whatever and you select bar 81 in the bounce window to end it will not line up.
So, I resolved playback start and lining up the markers by using these methods only to find that when navigating the markers in playback there were stutters almost as if mainstage couldn't cope with it and wouldn't navigate smoothly. Perplexed at this new hurdle (I already got me a copy of ableton live at this point) I was out of ideas. Luckily I had 2 versions of mainstage - the newest version (2.1.3 (416.81) and the older version 2.0.1 (408.12). I can't remember what made me try the other version but guess what?? It worked perfectly. Plays as it should, navigates the markers without glitches and lines up (that's a logic export issue anyhow I think).
Playback cold start is an easy one once you understand about mainstage clock, markers took a little while to figure out and glitches or playback multiple playback starts are trickier as it's a fault with the program version. As well as small glitches it would actually cut the current playing bar until it had 'figured it out'.
My older version was an option I think on upgrades - keep original version.
If you don't know the basics of playback as regards setting up sync and tempo info etc there are posts that cover this but if you've done all the bits I've done you should be fine. Shame about the version issue bug as it makes it unuseable and to be completely honest I don't trust mainstage for my purposes. I had Ableton Live session view doing what I wanted with a midi floorboard in about half an hour - no glitches and no messing, quick and easy and you can just put an uneven loop in there and line it up to play perfectly in no time at all.
Hope this helps ;0)
