Why is my camera taking so long to switch from Sub to Main?

[rrands1]

As the Title suggests, my camera (IPC-T5442TM-AS-2.8mm) is taking anywhere from 30-90 seconds to switch from Sub to Main when I maximize it in BI console, and also UI3. It eventually does get there, but in the interim, it's super blurry, and I can't see what I am after. I have other cameras on the same system that do not take this long, and I have played with the settings until the cows come home. Any ideas on why it takes so long to switch? Thank you for any help!
Sub:



Main:

 

[wittaj]

One reason is if iframes and FPS don't match.

Another is if using non-standard codec like AI, Smart AI, etc.

Another is using VBR instead of CBR

Another is camera going thru the router and waiting for enough bandwidth to open up and send.

Another is a buggy version of BI.

I am sure there are more, but these are what I mostly see here from folks.