Hi,
I will take a guess that the issue is when you are viewing them with IVMS,
I have had a long history with this software, when dealing with 96 2MP
cameras the software seems to suffer.
The telling sign, when there is a delay on IVMS, use a web browser to log
into the same camera and the time stamp will be different.
Give me more info on your setup and maybe i can suggest a few tweaks.
Regards