Need help in reducing my TTFB of ~4 seconds

Hi!

We have a website that is running WordPress with Woocommerce (https://pcx.com.ph/). I have a W3 Total cache configured as well as the Autoptimize plugin. I'm also using Cloudflare (free account).

When testing with GTmetrix, we normally got around 4 to 5 seconds of TTFB.

https://gtmetrix.com/reports/pcx.com.ph/DPvewhl1

I tried removing other plugins that we don't really need and replace others with a much more faster alternative plugin. I'm eying my server configs as I only based on them on recommendations from other websites but I'm no expert on these things so I really can't tell…

I was hoping you guys could give me some ideas on where to start.

Here's my
fcgid.conf: https://pastebin.com/9bLJ5C9D
apache2.conf: https://pastebin.com/QVMXeuXt
my.cnf: https://pastebin.com/NPvs48jd
php.ini: https://pastebin.com/PbZVCkHX
mysqltuner: https://pastebin.com/VWyUrk3E

Operating system: Ubuntu Linux 14.04.4
PHP version 7.0.29
MySQL version 5.5.62-0ubuntu0.14.04.1-log

Thanks!