Seems to be working!
As far as I understand it, the way W3 Total Cache works for fragment caching is that it writes finished files to the cache – and then serves up the file directly without regenerating them from the database if a browser asks for them.
The fragment cache works by looking at the file that’s about to be served up and seeing if the mfunc
code is there. If it is, then it inserts the up to date information – in this case the Rotating Tweets.
If the file in the cache is gzipped up (i.e. if the option to ‘Enable HTTP (gzip) compression’ is ticked) then the file in the cache looks like gobbledegook to W3 Total Cache and it doesn’t know where to put the Tweets.
So to get the mfunc
functionality working, you will need to switch off HTTP compression. Browser caching will also delay the time it takes before people see new tweets, so you may want to switch that off too.