The settings below are tested in production for 500 to 20.000 products and 3 mio attributes. To have a flexible and better server features management and also the best speed for to work with Prestasho,p take a dedicated or a VPS root server. Managed servers in most of the cases don't have the possibility to make own changes needed on the server configuration.
You need at least php 5.6.30. Better performance you will get with php 7 and mySQL 5.7 or mariaDB 10. There is no need for accelerators, in contrary, best is the use of php-fpm + opcache + ngnix proxied.
At least php 5.6.x + php-fpm + opcache with its own values (see below), better perfromance with php 7.
PS 1.7.x in detail:
PS 1.7.0 > 1.7.3. - here you can still use php 5.6.30 (above and inclusive) without problems. For better performance use php 7.1. and mysql 5.7 or maria DB 10
> PS 1.7.4. - explicitly requires php 7.2. and maria DB 10 or mysql 5.7.
opcache.revalidate_freq = 0 opcache.validate_timestamps = 0 (comment this out in your dev environment) opcache.max_accelerated_files = 7963 opcache.memory_consumption = 192 opcache.interned_strings_buffer = 16 opcache.fast_shutdown = 1