Virtual server - connection behavior changes based on the modifications

I am assuming that you are clearing up any persistence records and connections on the browser, waiting for a short period of time before initiating any new test.

A browser opens up multiple connections as seen here.

Although you believe it is an existing connection, the browser has its own behavior that is "optimized" to deliver objects based on performance variables like latency. In other words, I think the browser based test may not be a reasonable reflection of what you want to test. May be try other cli based options where you have greater control ?