LOTS AND LOTS of folks here in the forum lend assistance to those struggling with setting up things to reduce latency, but in all cases things like the following are needed to be provided by the person posting the problems:
1. Windows - what version (7/8?), what bit-level (32/64?), is your Windows installation at current Microsoft maintenance levels for patches?
2. For computer itself for latency issues: information on how much memory, the processor, any video cards, any other cards, disk drive types and speed, and configuration of drives (what types of programs/data are loaded onto each installed drive on the computer). There may also be software running in the background that is interfering with things, such as anti-virus software or other process-intensive tasks. In addition, for Windows 7 you can download and run the DPC Latency checker - freeware that displays a running graph of latency detected on your system, and will let you know if there are latency problems with your current system's configuration. For Windows 8, a different program is needed - LatencyMon is another freeware program that works fine on Windows 8 to provide you actually quite a bit more info in the same vein.
3. For the audio interface: info on the EXACT model of interface, the EXACT driver and firmware versions installed, if it is a PCI/PCIe connection to the computer, if it is a USB connection to the computer then do you have is plugged into a USB 2 or a USB 3 port. Also, what are the settings for Sample Rate and ASIO Buffer Size - (sometimes the buffer may be set using something like 'Number of Samples').
4. For Sonar: 32 or 64 bit version installed? In Preferences, what are the current settings for Sample Rate and record bit-depth, and what are the displayed values for the Latency (reported interface latency and total round-trip latency? And, please detail PRECISELY what plugins your project is using, as some of the plugins will cause massive latency in recording tracks. Some of the plugins are meant to be used post-tracking, such as for mastering. (some use look-ahead processing, which will kill you for latency during recording of tracks). And, have you tried a simple proejct, with just an audio track inserted and an MP3/WMA song imported into the audio track, then simply played back to check for distortions or latency?
5. Are you possible doing direct monitoring? If so, you will hear latency due to the time it takes processing to occur in Sonar. If you are, then you want to change to monitor Sonar's output.
Sooooooo, original poster, please review the above and respond to all of the above, so that we can do our best to assist you.
Bob Bone