How to decrease the boot time ,i mean 10 sec. to 2 sec or less .In ubuntu is very easy but i don't no in kaos .
You mean the bootloader delay time? Just type h in the bootloader menu, it will show you the options, or type t (or T) to adjust boot delay directly.
You can even edit a simple file for this, /boot/loader/loader.conf and set timeout there (default is 10 seconds).