I do not use Redis. But i think you can test “redis.sock” instead of the socket “localhost.6379”.
Read
Problems with config.php and Redis
For other settings search “redis.sock” in this forum.
https://help.nextcloud.com/search?q=redis.sock%20order%3Alatest
Additional:
Have you activated PHP Caching?
Search “Enable PHP OPcache” in https://docs.nextcloud.com/server/19/admin_manual/installation/server_tuning.html