A client's website started showing this like a week ago or a little bit more.
I tried disabling plugins, components, etc. Nothing worked until I figured out that it happened only to logged in users who were working on the site and also trying to see frontpage.
On my Joomla config, I changed the settings to PHP, reduced the cache time to 5min and set the Shared sessions to off.
So far, I haven't had any issue with it but I'm still monitoring it.
I have to be honest. Joomunited develop really good components and modules. I've suscribed to several of their products for more than 3 years but... their tech support lacks a little.
Well. My SocialBacklinks stopped working but I had the same configuration on several websites. I tried disabling cache, minifiers, etc. In the end, after several days, the criminal plugin was ShLib from sh404sef. I had to uninstall sh404sef completely and it started working again.
I spend the last 7 days looking for a way to lower the Time To First Byte (TTFB) on a website. It was taking from 79 to 90 seconds everytime you loaded the site for the first time.
My site is configured with:
- PHP 7
- Apache 2 + gzip + mod_ssl + mod_pagespeed + memcached. Pagespeed using memcached too.
- OpenSSL + a Comodo certificate
- 10GB Ram + enough hdd space
After the first load, the site was loading extremely fast in less than 3 seconds.
It wasn't the server. It was the Joomla configuration. I also had the JCH Optimize plugin to compress everything but I wasn't paying attention that on the first load, the site was packing all the images before displaying the site. I had to enable the images lazy load optionto load the whole page and then the images.
After this change, times dropped to an average of 10 seconds on the first load then about 3 seconds on internal pages as you were navigating the site. This worked for some weeks but the server kept failing.
I had to disable JUX Social Counter module that was used to show live numbers of our social media pages. This was the real cause of the long TTFB.
Third run (final):
I changed hosting provider to Knownhost, changed Apache for Litespeed with cache and changed the database to MariaDB. Loading times dropped from 30s. to less than 5s. with the same load.
TTFB on a Joomla site with an average of 6k visitors a day with more than 100k articles on database can bring some problems you won't experiment on development or with a small server. Plugins start to play an important role on loading time, if you have outdated plugins it's better to update them to latest version.
Memory, configuration, modules, compression it all plays a role here. I found that switching to a SSD hosting with cpanel (Knownhost I really recommend this) reduced the loading time and general response to less than a third.
I decided to test Litespeed webserver + litespeed cache (there's a tweak you have to do to use it with Joomla) because I was tired of configuring apache back and forth. It really worked fast and stable.
When you have a lot of content, databases need to be optimized too. Mysql is the default but it's joins aren't as good as MariaDB. It's an easy upgrade with a WHM+Cpanel hosting. This was the final trick.
I dropped the shs404sef component, installed Speedcache from Joomunited and used the core SEF. Site speed improved a lot, less crashes.
Update june 14th, 2018: After trying JoomUnited's speedcache, Varnish, sh404sef, JCH Optimize... we came into a conclussion that LiteSpeed Cache is the BEST cache provider. Of course that you need to be hosted on a server with LTS installed instead of Apache, Nginx, IIS. We offer LTS to all our clients as well as LTS cache.
Comparission between Varnish and LTS? Wow... Varnish is the closest contender to LTS but still a 2nd place with a huge gap in front of it. Not only the configuration of the default.vcl is a pain in the butt, but the hated Guru errors that showed up to clients harming your ranking, traffic and reputation.
Litespeed cache is now available for Joomla!: First of all, make sure you have it on your hosting (hey, we offer it b default to all our clients!) and it's configuration is super fast. We've been trying the ESI modules on some of our clients and on this page too and the loading time drops almost by half.
Ha! On this same page we had an issue that prevented of from using Yootheme PRO's builder on our own pages.
Solution: I found out that one of my cache engine was minifying and grouping JS and CSS. Removed it and it's fixed.