Time taken in between requests

Hi,

I have a scenario where I need to find out time take in between requests (to calculate transaction time).

Can we calculate time take between 2 requests (for instance we clicked on a link and the time taken for an image to be served on page). Here the 1st request would be clicking operation and next request would be the image request/response. The time taken in between these 2 requests needs to be captured.

Thanks.