Raspberry Pi isn't the Single Bord Computer I would use to do hosting, the storage side isn't efficient as almost all other SBC, and is ARM based like MattProd have said.
For low power hosting a Intel NUC or a similar devices will be way more efficient, and won't cost much more to run (few W more of power).
To help on the limited rPi, try first to install a minimal install of Debian. Raspbian is good for beginner, but heavier than needed to to hosting. (Rasbian is right between a minimal Debian Desktop and a minimal Debian)
Then remove anything running that not 100% needed. You can use "ss -putan" to see all network listenning process and "ps aux" as root and all running process ( ⚠ kernel and system process are on the later).
If possible (would be the case if you do a from scratch install of Debian), you should only have SSH and postfix listenning on the network, kernel and few non-removable system process, that's all (of course no graphical interface, nor display output, all of this is waste of CPU cycles). (+of course needed software for your workload)
You can look at process running in a freshly installed LXC container from the official Debian Template to see witch process are keept).
Bonus tips: disable automatic install of recommanded package (just install bare minimum dependency of your required software), and when possible use official repository (like the one from mariadb, deb.sury.org for PHP, ...).
