My site's ttfb is very high.
I used to use JCH-optimize plugin to enhance the page load. Then when I enabled Joomla's system-cache plugin, TTFB reduced to less than 1 second. But then after a while suddenly it got up to 3 or more seconds.
What ways are there to analyse TTFB in a Joomla site? How can I realize what component or what part of the site causes this?