Seconds matter an awful lot to me. If things don't happen fast enough, I end up alt-tabbing to the browser, losing my train of thought, and perhaps wasting a few minutes browsing the web.

I also work semi-offline a lot. My current internet connection is roughly 100 KBps. The connection in the underground isn't much better. I also work in airports and hotels. These pages that take 10+ seconds to load end up being abandoned.

Amazon famously measured how slow pages correlate with lost revenue.

You don't really notice this until you use something significantly faster, and you can stay focused on the task much longer. Things just work better. It's like using a sharp knife for the first time.