It doesn't happen when my ASIO buffer is set to 512. 

This problem is specific to his drivers, driver settings, PC and project. 

I had the same issue.  Upgraded to X2 from X1 and noticed this issue when I used Diminsion Pro on a track.  As soon as I "froze" the synth, the problem resolved itself and the project would play as normal as soon as I hit the spacebar.  Also tried setting my ASIO buffer to 512, didn't have any affect this time, but great advice all the same!  On big mixes, it helps for me to sometimes shut down ALL windows services under the "MSCONFIG" command... 

Have you pressed the "Pause|Break" key lately? I have inadvertantly pressed that key while using SONAR and the playback gets delayed (and the Now Time line becomes jerky). Pressing the key again and everything is back to normal. Supposedly, there is some performance reason for using that particular key command when using SONAR, but in my experience it only degrades performance.

Cheers,

Billy Buck

Pressing the Pause key toggles a feature that takes processing power away from the graphics display and lends it to the audio engine. This is supposed to improve playback performance on older systems. Not sure if it's really needed today with the power we now have in our PCs.

Scott

--
Scott R. Garrigus - http://garrigus.com
* Author of the Cakewalk Sonar and Sony Sound Forge Power book series: http://garrigus.com/?PowerBooks
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Also tried setting my ASIO buffer to 512, didn't have any affect this time, but great advice all the same!  On big mixes, it helps for me to sometimes shut down ALL windows services under the "MSCONFIG" command... 

Setting an ASIO buffer to a high setting of 512 inst the answer. If anything the ASIO buffer needs to be at its lowest setting possible. 

From what i'm quoting you, it seems like your PC cannot handle it, if you need to shut down ALL window services, in conjunction with your driver settings and the quality of the driver that is written (coded) for your sound card.

Hi vaultvit,
I had the same occurrence with my saffire pro 40.
This delay has disappeared with the last driver update
for the saffire (3.0).
I guess, Focusrite is working on it.
Often Matt- Focusrite, a forum member, joins in in such cases.
If you have not done it, I would recommend you to contact focusrite´s customer support, 
they are OK.
regards