Here are a couple of thing I have done to reduce latency. If i am using lots of processing, reverbs, effect, compressors, guitar rig etc. I freeze the tracks. This will free up psome resources so I can reduce my ASIO buffers down to 256 or 128. Or I just simply turn off reverbs etc. on a couple of occassions, I have bounced a stereo mix, used in current project, or created a new project with the 2 tracks bounced and recorded vocals, and then imported them back into the main project. However, that was when I had a single core computer / sonar 5, a few years ago. May not be ideal, but ut has gotten the job done. There is probably better ways to do this, however I haven't figured them out yet. hopefully someone will post it.