FastCGI Cache not working

Hello people,
As the title say, I need some help in setting up FastCGI Cache on my VPS but I'm having some problems. I configured my nginx.conf and site conf file but when I run ab benchmark I get worst results than without FastCGI (time per request, requests per second etc). The VPS (Debian 9) and ab benchmark (Mint Linux) servers are in the same network, but on different VLANs.

Attached are my nginx conf files if you need to take a look.

Thanks in advance,
Adrian