I worked for an ISP in the late 90s and we built a call center app using IE6, SSI, XMLHttp and also IE's built in CSS classes that matched the Windows colours t

I worked for an ISP in the late 90s and we built a call center app using IE6, SSI, XMLHttp and also IE's built in CSS classes that matched the Windows colours to essentially have a UI that looked and felt like a Windows 95 app.. It was completely unnecessary (at least the look and feel part) but the ability to load in new information into the UI without a full refresh was great. At the time this was running on Apache 1.1 via Perl CGIs and backed by an mSQL database (that was single-threaded!) so we wanted to minimize complex SQL queries as much as possible.. We eventually moved to a system that would batch pre-render customer details and call history to static HTML overnight when our call center was closed, to reduce the startup time of bringing up a customer's info when the agent had them on the phone. Then for that day we'd use XMLHttp to dynamically append new information from the DB (using a limit statement) and then re-build the static files the next night etc.. In hindsight, we did some creative problem solving for a bunch of self-taught 20-year-olds in the 90s.