Difference in Reponse time in TruClient & HTTP/HTML protocol

On execution of LoadRunner script I am facing the following issues:

I have created a script using TruClient-IE protocol for one of our release which is on ext-js. After executing the same on controller the response time is drastically high as compared to what I am getting using HTTP/HTML protocol on another release which is on XML on the same transactions or even when I am executing the same transactions manually.

With TruClient protocol it is as high as 16.99 seconds with 1 Vuser whereas when the same is done with HTTP/HTML protocol it is 3.183 seconds with 100 Vusers. Even when I am verifying the same manually it is not more than 3 seconds for the same test case. In both the cases think time/ wait time is same.

Also while executing, my Controller & Load Generator are two different machines.

Also when I scripted gmail login the response time with TruClient is 9 whereas with HTTP/HTML protocol the response time is 0.4 for the same transactions.

Please help me to know if I am missing something or if its an issue with Protocol.