Pushing MODX to speed up

Greetings!

I've got a fair result in page speed test results like in
webpagetest.org/
tools.pingdom.com
https://developers.google.com/speed/pagespeed/insights/

I've test other website that used other platform (not modx) with the tools above
and they failed, yet their site is loading faster than mine.
Why.

Hello,

You would need to give us some additional information such as the website(s) in question, what snippets your using in MODX, etc.

I'm using modx revo 2.2.11.
I have, mxcalendar, gallery, slideshow, and other typical
extras.

this was my first attempt
https://forums.modx.com/thread/89070/nivo-slider-and-phpthumb?page=2#dis-post-489958
in speeding my webiste. I optimize images I used in my landing page, as well combined other css.