I open a site and the plugin list is thirty one entries long. Three sliders. Two SEO plugins fighting each other. A contact form plugin, plus a second contact form plugin from whoever built it before. Something called Ultimate Toolkit Pro.
That is not a website. That is a landfill with a domain pointed at it.
What each one actually costs
Its own CSS and JavaScript, usually loaded on every single page whether the feature is used there or not.
Database queries on every request, sometimes a lot of them.
A security surface, because that is somebody else’s code running with full access to your site.
And a maintenance liability, because every one of them is a thing that can break when WordPress updates, and the odds compound. One plugin is basically never a problem. Thirty means something is always slightly broken.
The worst category
Plugins that load everywhere to do something in one place.
A slider plugin loading its whole library on your contact page. A form plugin loading on every blog post. Somebody visiting a service page is downloading the code for a feature that exists only on your homepage.
That is pure waste, and it is the most common performance problem in WordPress after images.
How I clean it up
List every plugin, then say out loud what it does for the business. If you cannot, it goes. Somebody installed it in 2022 to try something and it has been charging rent ever since.
Two plugins doing the same job, pick one. This happens constantly with SEO plugins and they actively fight each other.
Anything deactivated gets deleted. Deactivated code is still sitting on your server and still gets found by scanners. Deactivated is not gone.
And anything that could be twenty lines of PHP in the child theme becomes twenty lines of PHP in the child theme. I do that a lot. A file I wrote and can read beats a plugin with a settings page and an upsell banner.
What good looks like
A small site should be able to run on somewhere between eight and fifteen plugins. A store needs more, that is fine, stores are genuinely complicated.
The number matters less than whether you can name what each one is for. If you can, you are in good shape. If you cannot, you are paying the tax.