Recently I've run into this issue where midi timing and latency is becoming an issue in my system.  Two things have happened:
 
1) I've needed to beef up my mixing so I've been running Sonar with tons more heavy duty plugins...limiters, compressors, reverbs, amp simulators and iZtope's Ozone 5. They seem to be way bigger resource hogs than Virtual instruments.
 
2) My master keyboard of 22 years died,  I replaced it with a keyboard that has a lighter action.
 
The result of the added latency and lighter touch is I'm way ahead of the beat when I record midi parts.  I have to quantize everything I do now.  Sometimes I find the right number and can slide a performance back, say 30 ticks and if i get lucky the performance drops into the groove.  It's tuff turning off all the fx's cause things sound so different then.
 
Is there something I can adjust for this?  Is there a buffer I can change?  Or do i need to bite the bullet and upgrade my 5 year old computor?
 
Thanks,  this had always been the greatest place to get advice.        

Have you tried bypassing effect (E key) while tracking? Some plug-ins have "look ahead" on them that will insert latency on you by default. You can bypass effects to record, then turn them back on afterwards.
 
You can also manually offset latency, but if that is not consistent, it may not help as much as you would like.

Yea, I've tried bypassing the FX, but it is harding recording with things sounding so different. 
 
I should add that my RME sound card's buffer is set at 512. Anything lower induces the "pop and crackle" overloaded CPU issue we all love.
 
THanks mettlus... 

Just to clarify, It's not that the FX are so CPU-intensive, but that they use look-ahead processing with an internal buffer that adds to the audio latency. So getting a faster computer won't help except to the extent that it allows you to lower your ASIO buffer to reduce the total latency. But plugins that need PDC may use buffers that are significantly larger than your ASIO buffer so the net improvement may be marginal.
 
SONAR applies plugin Delay Compensation (PDC) to other tracks so that they'll play in sync with tracks/buses using plugins that require it. So all tracks in the project are affected by the added delay of plugins on other tracks. Aside from bypassing all FX in the project, another option is to enable PDC Override (Shift+E or click the PDC button in the Mix module) which disables PDC on input-monitored audio tracks (including soft synths) so you can rehearse/record without latency. This works so long as the plugin requiring PDC isn't on the track your monitoring.
 
Ultimately, though, you want to try to avoid using plugins that require PDC during the tracking phase of a project.
 

You could have two parts of a song.
 
So you have a song, export a mixdown.
 
Then start a blank project or create a 'lean' template with just what you need to record with.
 
Then import the mixdown, track to it and export your recording back to your original song.