Yesterday I experienced a massive problem due to the death of my EM-U 1616m audio interface.  I had to make a quick decision to head to Guitar Center and purchase a new audio/midi interface.  I chose the Presonus AudioBox iTwo.  I've used Presonus equipment before and it seemed to do fine.
 
Back to my issue...I've been running X1 and the first issue with the new AudioBox iTwo was latency problems with my keyboard and vsts.  Enough to just make you crazy.  After spending a few hours tweaking and updating things (upgraded to X1 Expanded with all the current updates) I was finally able to get the piano vst to work with very little latency...exactly what I've been used prior to all of this happening.   
 
Since I was on an upgrade kick I decided to purchase the Sonar Professional upgrade.  Now when I'm in this newer version my latency issues are back.  I have the exact same settings as in X1 Expanded and cannot figure out why it's worse in the newer version.  I have my buffers set at 256.  The sampling rate is at the max the interface will allow (96000).  The latency shown in the Preferences screen show ASIO Reported Latencies - Input 5.1 msec / Output 4.9 msec
 
So my decision right now has to be to continue with X1 Expanded...
 
I would appreciate any thoughts...
Thanks,
Richard
 
Sweetwater Creation Station with Asus P6 Deluxe and Intel i7. 12gb RAM, Windows 7, Garritan Steinway, Superior Drummer, Miroslav Philharmonic, Garritan Jazz Band, Marching Band

Are you sure you're comparing apples to apples in terms of what's in the project?
 
The most common cause of unexpectedly high latency is adding a plugin to the project that uses an internal buffer for look-ahead processing which activates SONAR's automatic Plugin Delay Compensation to keep other tracks in sync with the processed track/bus. You can click the PDC [override] button in the Mix module to bypass PDC on input monitored tracks (including live soft synths) so long as they aren't the track with the PDC-inducing plugin. But it's best to avoid using PDC-inducing plugins during the tracking phase of a project.

Another option would be to bypass all of your Fx by hitting 'e' on your keyboard.
This should tell you roughly what the natural latency is

Thanks for the replies...
I loaded a song file using an orchestral template I have set up over time and have used successfully for several years now.  X1 Expanded works just fine with all the typical fx that I have turned on when the file loads.  When I open the exact file in Sonar Professional, and the same fx are on I get a crackling noise and latency issues.  I turned off all fx and the crackling and latency issues have gone away.  So you are correct that the effects are the issue.  
 
I've also noticed I can't find the same fx in the newer program.  And as I'm writing this I am getting the white screen of death as tried to load a Cakewalk Reverb that was listed under Direct X.
 
So I'll still welcome comments and your expertise as I continue to flush out this issue.
 
Thanks,
Richard 

Default sample rate for new projects is 96000 in both versions? And ASIO buffer size is not changing? How about 64-bit Double Precision Engine; enabled or disabled in both? You might also check the setting of Always Stream Audio Through FX (roughly the equivalent of 'Play FX Tails' in X1).
 
If all else fails, I suggest you start disabling FX one at a time, and see if any particular plugin is driving the load in Professional. But load alone should not cause an increase in latency, just crackling as you described if the CPU cannot keep the buffers filled at the specified settings. So it sounds like maybe some synth plugin is misbehaving at the limit.
 
I suggest you use input monitoring of the Kurzweil's onboard sounds or another hardware synth to know what the latency is apart from any soft synth rendering issues.
 
 
 
 
 

rsmproductions
I've also noticed I can't find the same fx in the newer program.  And as I'm writing this I am getting the white screen of death as tried to load a Cakewalk Reverb that was listed under Direct X.

There is no mention before, are you running 32bit X1 and Professional?

did you migrate prefs/settings from x1?

This might be a case of benefitting from deleting or renaming the existing aud.ini file and let Sonar build a new one

Good suggestion, Jonesey. There have been a number of cases where SONAR 2015 didn't like the AUD.INI settings it inherited from an earlier release. Especially suspect in this case since the old AUD.INI will have all the E-MU config stuff in it.

scook

rsmproductions
I've also noticed I can't find the same fx in the newer program.  And as I'm writing this I am getting the white screen of death as tried to load a Cakewalk Reverb that was listed under Direct X.

There is no mention before, are you running 32bit X1 and Professional?

Yeah... worth checking whether either/both are 32bit vs. 64bit.