Thanks Sean, those options are all already employed on the site, the site is just hitting its limits in terms of dynamic content being served.
A few more tests today on TTFB comparing the same Wordpress site on Webfaction (Singapore) and on Opalstack (Frankfurt). Tests run at 03:10 UTC. This time around, the Webfaction server massively outperformed the Opalstack server, being about 55% quicker.
Webfaction:
Connect: 0.000 TTFB: 0.649 Total time: 0.703
Connect: 0.000 TTFB: 0.505 Total time: 0.550
Connect: 0.000 TTFB: 0.445 Total time: 0.487
Opalstack:
Connect: 0.000 TTFB: 1.151 Total time: 1.184
Connect: 0.000 TTFB: 1.057 Total time: 1.092
Connect: 0.000 TTFB: 1.104 Total time: 1.137
(all connections are local, from the same server to avoid network speed noise)
Command used:
SITES="a.b.c.d w.x.y.z"
for site in $SITES
do
echo "$site"
for i in 1 2 3
do
curl -o /dev/null -s -k -w "Connect: %{time_connect} TTFB: %{time_starttransfer} Total time: %{time_total} \n" --header "Host: example.com" https://$site/XXX
done
done