Is it possible to configure Varnish 4 to cache all content regardless of what it is? I tried what's mentioned here: http://www.atomictag.com/2016/04/25/varnish-cache-all/ but my hit rate is still low.
If this is possible I can then configure Varnish to refresh the cache every 15 minutes or so from the backend. I know this is not the best practice but I am ok with serving my website visitors content that's 15 minutes old, if I can increase the website loading speed.
The Varnish server has 32 GB of RAM but only 8 GB is used. I've configured -malloc, 25G.