Someone just came up to me and told me to load maps.nokia.com to see how fast it had got after our new server migration.
I opened up a new tab, typed the first few keys of the URL and bam the site was there - super fast! Wow! I check the network tab, 1.47seconds - amazing!
Then something strange happened, I cleared my cache and loaded the page again, no surprise, it took a bit longer without a primed cache. The strange part was when I reloaded again to get the super fast version. It was no longer super fast, it was a second or so slower than the un-primed version.
That’s weird, I thought.
I loaded again, no change. More weird.
I noticed that all the requests in the network tab had gone from being cached responses to 304’s so there was a server hit after all - but we have far future expires headers - this shouldn’t happen?
After some googling, I discovered my answer on stackoverflow.
When you use CTRL-R to reload a page, most browsers will send a 304 even to cached resources.
So as it turns out, the page was always caching resources and was always returning in 1.47 seconds, but ONLY if you reload the page by re-entering the url. Mystery solved.