dappa1
David same thing happens takes an eternity to load a simple song. Splutters and stops without apparent spiking.
Hope they fix these issues in there monthly releases. I have to wait until the end of the month to see improvements if not I will have to wait till the month after!!!

This post was completely misleading and unhelpful. This is a relatively new poster looking for solutions to a specific problem. By immediately blaming Sonar when there is a plethora of other possible (and much more likely) reasons you have done this individual a great disservice.
 
Sorry to call you out like that, dappa but that just isn't cool. If you are having your own issues then of course there are mountains of people here willing to help you sort them out.
 
Peace.

For the record, I have experienced the problem the OP is describing. Usually for me, the only cure is to close the project; close SONAR, and re-open it, starting a clean session. I always suspected a memory leak of some kind that only appears after a specific sequence of workflow.
 
I primarily use Dimension Pro 1.2 (DX); Arturia CS-80v; and MinimogueVA VST. My audio interface is Echo Layla 3G, in SONAR (x86) on Windows 7 (x64) with 8GB RAM.
 
But this is all different since a few days ago, and I haven't experienced the problem recently. Take it for what it's worth.
 
 

I would bet that you (the OP) have some kind of plugin conflict.
 
I had exactly the same problem, except that I could never get the project to play at all.
 
I have discovered that I have some kind of VST install problem because the culprit was the VST3 version of both Imperial Delay and T-Bone from Boz Digital Labs. I'm pretty certain that there is nothing wrong with these specific plugins, rather something is amiss in my installation.
 
To make everything run again, I removed the VST3 versions of these plugins from every project in which I had used them, and replaced them with the VST2 version.
 
This magically fixed everything.
 
I think it is some kind of installation mistake where the 32-bit versions of these is getting referenced in a 64-bit world, but I'm not really sure. I know that the VST3 install path is different, but I don't know how to differentiate the 64-bit VST3's from the 32-bit VST3's, if there is such a thing.
 
Perhaps a member of the Illuminati could shed a little light into our prevailing darkness. >8]
 
ADVthanksANCE
 
-Jack (gee, it's dark in here...)

I have occasionally ran into a problem that sounds like what the OP is reporting.  For me, it seems to be related to the Concrete Limiter (or another PC VST) in the ProChannel, usually on a bus.  My current theory is that it has something to do with upgrades resulting in multiple copies of VSTs laying about my computer.  The fix that seems to work for me has been to remove the Concrete Limiter from the PC and then re-insert it (note the settings before removing).
 
I'm thinking that this may also be happening when I work on a project in multiple versions (X2, X3, SPlat) of Sonar.
 
Disabling effects globally ("E") tends to turn it off, re-enabling them brings the problem back.  Turning off the PC on the problem channel does the same thing.  If this is the case for the OP, try reloading your PC modules and saving the project.
 
Glen