Yes, there are a very small number of plugins that are on a "hard ban" list. These are mainly plugins that duplicate services that run directly on our servers, or have been evaluated as causing serious security or performance problems.
We are always looking to protect your site performance and its environment, so we ban plugins that would compromise that!
There are also plugins that we strongly recommend against using, but don't outright ban. If one of these plugins is causing problems on your server, you'll be informed by Performance Foundry staff. If an alternative can't be found, you may be asked to deactivate the plugin or move to a different hosting tier to allow the processes to be handled with the right level of hardware.
We reserve the right to disable plugins or themes, or even take a site offline, to protect the greater environment. This happens very seldom. To date, we've never had to disable a site. (Touch wood!)
We see a lot of poor performing themes and plugins coming through our systems. We highly recommend you avoid these! They're responsible for a lot of the performance issues we see.
Where we have a good recommendation for replacement, we add it. Recommending a plugin does not guarantee it's perfect, just that it's a suitable swap for similar features. Consider removing the feature if it's of no/little value to your visitors or business needs.
These plugins generally do something poorly that causes each pageload to use significantly more resources than is needed. We're looking for ways to help your site scale; giving you more traffic without more costs. These plugins stop us doing that.
We'll write more on scaling in the future, but as a shorthand, things that use admin-ajax or write to the database are hard to scale, as 1 visit = 2-50x the resources per visitor.
Social share counts: Doesn't matter the plugin, social share counts are painful to your performance. Turn them off.
instagram-feed and instagram-feed-pro: A plugin for displaying a live instagram feed. These plugins send 3x admin-ajax calls per pageload. Replace with https://wordpress.org/plugins/wp-instagram-widget/
top10: A plugin for displaying your most popular posts. This writes to your database on every visit and fires an admin-ajax call to do it. If you already use Jetpack stats, switch to their popular posts widget. If not, Performance Foundry has a beta plugin that uses Google Analytics data. Ask support about using it.
woocommerce: A plugin to add e-commerce to your site. It makes sense that adding an entire e-commerce suite to your site will add some resource usage! If you're not using it, deactivate it! If you are only using it on part of your site, talk to support about limiting the scope of the resources it loads and ajax calls it makes.
It's hard to generalise with themes, as there are so many options. We've seen problems with sites scaling that use Divi, Elegant and Thrive themes. Avoid. Basically, more options = more data throughput = slower/more expensive for the same results.
We disallow a few plugins that can cause performance problems for our servers. This is mostly due to high disk and/or database usage.
You can view the current list of banned plugins below; we reserve the right to add new plugins to this list at any time.
These plugins are resource hogs and we suggest using Google Analytics instead.
These plugins conflict with our own robust nightly backups to Amazon S3.