Fully loaded Time issue with GP Premium

Hi,

First of all I know that GP is a fast theme. I use it on all my websites and client's websites and I can say that I manage to get really good speed results with it.

But I have a really weird issue with one of my websites, GP Premium is causing a Fully loaded Time issue.

I worked around to understand what what causing this result and couldn't find anything until I tried to deactivate GP Premium plugin and boom, fully loaded Time dropped down drastically.

Here are the tests I did :

First test is with GP premium ON and all my other plugins OFF >>> 4,4 sec
Second test is with GP premium OFF and all my other plugins ON >>> 1,7 sec
Third test is with everything ON >>> 4,4 sec

I also tried to install GP premium 1.2 back to see if 2.0 version could have caused this.
But exact same results.

I can tell that this tests has been done without changing any other configuration on my website. Just activate and deactivate GP Premium and/or other plugins.

What is weird is that I have GP premium on other websites and it's not causing this fully loaded time issue...

So I don't understand what's going on, but if you already see this problem, and now what could cause this, I fully interested to know your thoughts.

Thanks for your help.