I have no latency problem with SONAR 8.5 (Win 7 32 bit) using ASIO until I get above 12 tracks or so. That's usually when need to do vocals and the latency is noticeable. I freeze tracks which I believe helps the CPU usage...not sure if that helps latency. I thought there was some way to disable tracks you don't need to hear temporarily but I can't remember what it is. I know you can disable effects. I'm looking for any trick(s) to get through the vocals with low latency. I can enable effects or tracks later for the mix when I don't care about the latency. I can do the vocals with no problem if I can hear only 4 tracks.

Latency is only an issue if you have checked input echo and monitor the recording AFTER it is recorded. Turn OFF input echo.

 Of course you will hear latency as all systems add a few Ms as the signal is run through all that conversion and processing. EFXs make it even worse. 
PS   Ctrl/shift/Y bypasses all EFX bins 

If you have the same Fast track I used to have-  then you need to use the MIX control to blend the input with your computers output. Sonar automaticly adjusts for system latency so that the output will sync with your newly inputed signal. That is what is called direct monitoring which has zero latency. 

The Ctrl/shift/Y suggestion is a good one. This is the M-Audio model I have. I know how to use the mix control...it just sounds much better to me for an electic guitar or almost anything to have effects monitored while you do that recording take. What I did is to select all tracks and copy them to the clipboard. I then opened up a new project and pasted it all there. Everything was now on one single track. That allowed me to add a vocal with no latency problems. When I was finished the take I copied and pasted just the new vocal to the original project for mixing.