Unfortunately, I didn't have free time to answer earlier.
So, I see next. Our application works faster on Chrome than IE. I see it using my eyes and can say that refresh of contents, pages rendering are faster, absolutely if the browser is not run by Test Studio for tests. If so, loading of the main page and any other work with the pages is slower. Much slower because I can see it my eyes.
I checked on https://telerik.com too. The main page loaded faster if the browser is not run by Test Studio for tests.
I made a very simple test project for you. The test loads https://telerik.com page, clicks on DOCS link and waits for some elements as visible.
I run one twice and see something like that results.
Test duration: IE Chrome Firefox (in seconds)
10 72 40
You can see the results in the attached project.
I tested the project on two environments:
1. Windows Server 2012R2, IE 11.0.9600.18793, Chrome 64.0.3282.186 (64-bit), Firefox 58.0.2 (64-bit)
2. Windows 10, IE 11.248.16299.0, Chrome 64.0.3282.186 (64-bit), Firefox 58.0.2 (64-bit)
For Chrome was used "Progress Test Studio Extension 2017.3.1003.1"
For Firefox "Progress Test Studio Extension 2017.3.103.1" by Deyan
I need fix this problem as soon as possible.