My company is developing a web-based data viewer application which requires a fairly decent amount of bandwidth to function well. However recently we have been changing a lot of things. For example, we changed our internal network infrastructure so that data can be hosted on separate machines connected by Gigabit Ethernet. On top of that, the application itself keeps coming out with new versions since we are still in alpha and beta testing.
Recently we made some changes that are causing poorer performance, and we want to try to identify where the problem is before we start tearing things apart. It is a very small network, and I have limited experience as an IT admin. I have a few ideas for where to start, but I would like to harvest a little wisdom from the pros first: How do you tackle/avoid similar problems? What are the most useful (Windows) tools you have used?