Yes I have enabled. Since my last post here, I setup MaxCDN mirror for CDN. It helped very little by reducing the first byte to 6.5 seconds. MaxCDN support guys were great and they helped look through my w3TC plugin setup and said it was configured just fine.
It seems the images are still being rendered from the origin server (my website) rather than the CDN. It may be timthumb.php issue where it is not a variable for the image folder. I am using Advanced News Paper theme.
Any suggestions on how I can fix it?