Hello there,

Here are some general tips for speeding up your website, and please note, you can't minimize files like js.php and css.php, because they are dynamically created.

1) You can check how to optimize your website here: (in this part, minimization of those files will be mentioned): https://gtmetrix.com/ as result we got message that it is highly recommended to optimize images https://www.screencast.com/t/50Cm9qlvQ2G

2) Optimize your images with some too like
www.jpegmini.com/ withput loosing image's quality

3) Also you can install some plugin for cache, like WP Fastest Cache:

https://sr.wordpress.org/plugins/wp-fastest-cache/

http://wordpress.org/plugins/wp-super-cache/

https://wordpress.org/plugins/w3-total-cache/

or premium one http://wp-rocket.me/

4) You can enable gzip compression on your server. You should paste this code to .htaccess file located in your folder:

<ifModule mod_gzip.c>
mod_gzip_on Yes
mod_gzip_dechunk Yes
mod_gzip_item_include file .(html?|txt|css|js|php|pl)$
mod_gzip_item_include handler ^cgi-script$
mod_gzip_item_include mime ^text/.*
mod_gzip_item_include mime ^application/x-javascript.*
mod_gzip_item_exclude mime ^image/.*
mod_gzip_item_exclude rspheader ^Content-Encoding:.*gzip.*
</ifModule>

http://www.feedthebot.com/pagespeed/enable-compression.html

5) Leverage browser caching:
http://www.feedthebot.com/pagespeed/leverage-browser-caching.html

6) Use ate least PHP 5.4.x or greater in order to process PHP code faster, and to fix older version bugs. Note that wordpress is now recommending PHP 5.6 or greater https://wordpress.org/about/requirements/

Please let us know if this was helpful.

Thanks.