this extension requres Redis Magento Builtin cache enabled and php_redis php extension installed. The phpredis extension provides a native PHP API for communicating with the Redis key-value store.
#RHEL / CentOS
#Installation of the php-pecl-redis package, from the EPEL repository:
yum install php-pecl-redis
When I developed a Shopware 6 based website I noticed fast sub 1ms performance of the FPC cache. I checked the code and it amazed me. It is simple and made a right PHP way! You don't need Varnish to run your FPC cache fast. You need just fast code without reusing the Magento 2 junk core framework.
Nginx
fastcgi_param PHP_VALUE "auto_prepend_file=/var/www/html/magento/app/code/Mage/FPC/FPC.php";
/var/www/html/magento/app/ shuld be changet to your magento path
or
add it as a first line to app/bootstrap.php or pub/index.php
Also if you are using composer to install this stuff your path will be something like : ../vendor/mage/fpc/src/Mage/FPC.php
Installation into app folder is preferable. It is not a usless library. It is a part of your busines to keep your site FAST.
require "../app/code/Mage/FPC.php";
Also this extension will work without this aditional interactions (jsut install and forget) but it will be slower becouse it will load all Magento 2 via autoloader.
or do next:
composer require mage/fpc
bin/magento setup:upgrade
bin/magento fpc:deploy
FPC generation time is 0.000481128 second.