I responded to a forum post and put so much information I thought I should post it here too, please comment and I can flesh out the posting with information people need me to elaborate on…:
Here is my recommendations:
Fix any 404 issues. Generally you can right click in a browser, inspect element and then go to the console which will show you issues to fix.
As for plugins…:
– I would look at tinypng to optimize images in the site. It has better compression than shush.it in general and smush.it seems not to be commercial and gone to the dogs.
– Speed Booster Pack – Its relatively easy to configure and you can tell it to minify css, js and load js in footer, you can lazyload images and is relatively easy to setup.
– Use htaccess to tell web server to cache, turn on gzip compression. AskApache.com has a load of good info, I dont know where to go if your host is using NGINX… anyone?
– Use a cache plugin of some kind, I find W3 Total Cache to be overkill and to hard and if mis-configured it can be harmful.
– Optimize database after deleting revisions – A plugin that not many people think of but you can schedule a cron to run and it will clear out revisions and other crap on the database before it performs an optimize, it can clear out MB’s of data and make SQL queries run faster.
– Use a CDN, Islandhosting.com allows you to configure cloudflare in the cPanel for free and can really help.
– As your hosting provider to help you see what might be causing slow loading, at Islandhosting.com we will look into it, we can turn on newrelic stats and profile the site and find out what might be causing the slow loading. We can then determine if creating new indexes in the database structure could speed things up or if you have an offending plugin you should remove.
You could try turning off all the plugins and then turn then on one at a time to see when the site starts to crawl, there are also plugins that will let you profile performance of the site.
– Make sure you don’t have spam user registrations and/or comment spam building up in the back, check your users section in the dashboard and turn off user registrations if you don’t need them and use a plugin like “disable comments” if you don’t need comments on.
– Make sure your site is not getting slammed by spam bots or brute force attacks which can put load on the server and make the site perform slow.
– Check the resources in your account, make sure your on a plan that gives you enough entry processes, bandwidth etc, we can help our customers with this at islandhosting.com
– malscan your site, if you have malware it can cause unpredictable results, Islandhosting can run a maldet and a clamscan detection on your site for free and help you if you have malware. You can also use securi to scan your site and they also have a plugin for wordpress.
– Make sure you don’t have any plugins that keep logs that have been building over time and have not been purged. I had a site using 404 redirected and the log file tables got massive and the site crawled.
– disable wp-cron in the wp-config.php file (google it to find out how) and then add a cron in your web hosting control panel to run periodically, wp-cron runs on every page load and can be an overhead you don’t need. Some hosts wont even allow wp-cron.php to run.
– WordPress Heartbeat can also be a performance problem, I have seen it in some sites before. See http://wptavern.com/how-to-take-control-of-the-wordpress-heartbeat-api, there is a plugin that can help therein.
I think I have covered all the things I have faced that effect performance, had to help allot of customers with performance issues in the past and I have learned a few things!
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