How to find the WordPress plugins that slow your site
Each plugin can add scripts and styles to every page. Measure what each one costs and load heavy ones only where they are used.
Step by step, with screenshots: Too many plugins in WordPress? Measure what each one costs →
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What it is
WordPress plugin cost is the weight each active plugin adds to your pages: the CSS and JavaScript files it loads for every visitor, whether the page uses the feature or not. A slider, form builder or social-sharing plugin can add hundreds of kilobytes to pages that never show a slider or a form.
The number of plugins matters less than what they load and where. Twenty light plugins can cost less than one heavy one that loads its scripts site-wide. Deactivated plugins cost nothing on the front end, although they should still be deleted if unused.
OK looks like this: no single plugin adds a large share of the page's code, and heavy plugins load their files only on the pages that use them. getReport attributes the page's CSS and JavaScript to the plugins that load them and names the heaviest one in KB.
What a passing site looks like
- WordPress plugin weight: passeswarning · −1.5 ptseffort M
WordPress plugin weight
Why it matters. Every active plugin can add scripts and styles to every page, whether the page uses them or not. A slider or a form builder can weigh more than the rest of the site together.
- Deactivate plugins the site does not use; for the heavy ones in the table, check whether a lighter alternative exists.
- Load plugin assets only where needed with a performance plugin (Perfmatters, Asset CleanUp) or the plugin's own "load on demand" setting.
Questions people ask
Why is my WordPress site so slow?
The usual causes are slow hosting (high server response time), no page caching, large unoptimised images, and plugins or a page builder loading heavy scripts and styles on every page. Test a page to see which of these applies: getReport shows server time, image weight and the cost of each plugin.
Do plugins slow down WordPress?
Some do. Each active plugin can add PHP work on the server and CSS or JavaScript to every page, but many add almost nothing. What slows a site is a few heavy plugins, usually sliders, page builders, form builders, social feeds and chat widgets, loading their files everywhere.
Do inactive plugins slow down WordPress?
No. WordPress does not load deactivated plugins, so they add nothing to page speed. They still take up disk space and, if they contain a vulnerability, their files can sometimes be reached directly, so delete plugins you no longer use instead of leaving them deactivated.
How do you find which plugin is slowing down WordPress?
Look at what each plugin loads on the front end: getReport lists every plugin's CSS and JavaScript weight on the page. For server-side slowness, a query monitor plugin shows which plugin's code takes the most time. You can also deactivate plugins one at a time on a staging copy and measure again.