I just realised I haven’t updated the site since our last big development. We’re now serving almost all of our pages from Varnish. Crude research suggests around 90% of our pageviews are now coming from Varnish. In simple terms, we’re doing did the following:
- Ajax all pages, so everything can be cached (with a few exceptions we manually exclude)
- Cache page variants for currencies and tax rate
We’re also warming / refreshing the cache using a bash script parsing the sitemap and hitting every url with a PURGE then a GET.
The hardest part of the whole performance space has been to measure the impact of our changes. But our TTFB was previously in the 300-500ms range for most pages, and now it’s in the 20-30ms range for pages that come from Varnish. I’m very confident that it’s impacting our bottom line.