IS ANYONE ELSE HAVING THIS PROBLEM? I HAVE DOZENS OF OLDER PROJECTS THAT STILL WORK FINE USING SAME  MIDI CONTROLLER KEYBOARD WITH NO LATENCY. NOW ALL NEW PROJECTS HAVE A BIG LATENCY PROBLEM. DRIVERS AND SETTINGS ARE THE SAME ON NEW AS OLD PROJECTS.  ANY HELP ON THIS?
                           FARMER GEORGE  NEW JERSEY USA

Most of the time midi latency is caused by having certain plug ins active. Try by passing your effects bins and see if it goes away. For me the LP 64 effects will cause a huge delay.

Yeah, this screams of a plug-in added to a project that shouldn't be used during tracking.  Cactus has the first step.  

Hitting the letter 'E' on your computer keyboard will toggle on/off the Bypass All Effects in Sonar.  Hitting it again will turn them back on.
 
It is a good place to start.
 
Is your Driver Mode still set the way you want it (ASIO, presumably) 
 
Bob Bone