Hello @nichere
Thank you for your feedback.
Yes, I can see that the W3TC is installed now and none of the settings are enabled currently.
The ttfb is huge, up to 3.3s I would recommend you enable the Google Page speed feature in the W3 Total Cache General settings, test the website there and you will find the W3TC recommendations for improving the performance.
To start, you should enable Browser Cache and cache control header, Page Cache set to Disk: Enhanced and Minify the files.
Thanks!