Speedup WP website customer

[inkoop@topmatica.nl]

A webmaster is bussy with speeding up a WP website. He's complains's about reaction time server is to low and his  ExpireHeaders are not working. He's using PageSpeed Google.

What can I do to speed up the server ?
How can I let the headers work?

First i like to check if there are other parameters to set in PHP, Apache, MYSQL etc  to tune my server.
Second, Is saw the possibility to install Varnisch. But this is something to do later.
and,
I am not a fan of WP but i could also advice WP Supercache .

Specs:
Digital Ocean:

Code:

Welcome to Ubuntu 14.04.5 LTS (GNU/Linux 3.13.0-43-generic x86_64)
 * Documentation:  https://help.ubuntu.com/
  System information as of Sun Sep  3 16:14:54 CEST 2017

  System load:  0.28               Processes:           85
  Usage of /:   39.7% of 29.40GB   Users logged in:     0
  Memory usage: 35%                IP address for eth0: xxxxxxx
  Swap usage:   0%                 IP address for eth1: xxxxxxxxx

Php 5.5.9
Loaded Modules:
core mod_so mod_watchdog http_core mod_log_config mod_logio mod_version mod_unixd mod_access_compat mod_alias mod_auth_basic mod_authn_core mod_authn_file mod_authz_core mod_authz_host mod_authz_user mod_autoindex mod_bw mod_deflate mod_dir mod_env mod_filter mod_headers mod_mime prefork mod_negotiation mod_php5 mod_proxy mod_proxy_ajp mod_proxy_balancer mod_proxy_connect mod_proxy_html mod_proxy_http mod_rewrite mod_setenvif mod_slotmem_shm mod_socache_shmcb mod_ssl mod_status mod_xml2enc

Zend 7.0.3

[Me.B]

Use super cache that will fix the website. Also use P3 (Plugin Profiler Performance) to check if a plugin is not killing it.

Usually I found badly written plugins that will be clugged with DB requests. I found a plugin from a big editor not using limit to pull conextual posts and with a blog over 100k posts it will kill the server. Few tweakes got back 80% of the resources.

M B

[inkoop@topmatica.nl]

Use super cache that will fix the website. Also use P3 (Plugin Profiler Performance) to check if a plugin is not killing it.

Usually I found badly written plugins that will be clugged with DB requests. I found a plugin from a big editor not using limit to pull conextual posts and with a blog over 100k posts it will kill the server. Few tweakes got back 80% of the resources.

M B

Thanks Me.B for the advice and information.

Does anybody know how I can enable cache in php?
phpinfo telling me:

HTTP Response Headers

Expires               Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control   no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma               no-cache