Why your WordPress site is slow and how to make it faster

In short

• Measure first, with PageSpeed Insights, so you know whether the problem is the server or the page.
• Most slowdowns come from large images, heavy plugins and no caching.
• Use a current PHP version (8.2, 8.3 or 8.4), and check compatibility first.
• Only when all of this is in order and the website is still slow at traffic peaks is it time for a bigger plan.

Step 1: measure

Open PageSpeed Insights and test the home page and one important page (a product, a service page) on mobile. Look at two things:

• Time to first byte (TTFB): how long the browser waits for the server to respond. If it's high, the problem is behind the website: PHP, the database, plugins, no caching.
• Core Web Vitals: LCP (how long until the main element appears), INP (how quickly the page responds to a click) and CLS (how much the page shifts while it loads). If TTFB is low but these are poor, the problem is in the page: images, scripts, fonts. What each number means, in detail: speed and Core Web Vitals.

Step 2: images

Images are the most common cause of a heavy page. A photo taken with a phone is often several megabytes and over 4,000 pixels wide, even though it's shown on screen at 1,200.

• resize images before uploading them, to the width at which they're displayed;
• use modern formats, such as WebP or AVIF;
• keep lazy loading for images further down the page, but not for the main image on the first screen.

The steps, using WordPress's own tools, are in the guide optimized images in WordPress.

Step 3: plugins and theme

Every active plugin adds code that runs on every visit. It's not the number that matters, but what they do:

• deactivate the plugins you no longer need, one at a time, and delete them;
• look for duplicates: two SEO plugins, two form plugins, two caching plugins;
• heavy page builders and “do-everything” themes load a lot of code on every page;
• external scripts (chat, ad pixels, maps, social widgets) slow the page down even if the server is fast.

Step 4: caching

Without caching, WordPress builds every page from scratch on every visit: it runs PHP, queries the database and assembles the theme. A caching plugin saves the finished page and serves it straight to the next visitors. On shared hosting the difference is big, because it directly reduces the need for PHP processes, and each website has a limited number of concurrent processes (5 on NBT Host web plans).

In stores, the cart, checkout and customer account pages aren't cached; all the other pages are. How to choose and set up a caching plugin: the WordPress caching guide.

Step 5: PHP

Newer PHP versions are faster and receive security updates. On NBT Host plans you choose PHP 8.2, 8.3 or 8.4 for each website, from Enhance. Before switching, make a backup and check that your theme and plugins are compatible; the steps are in the PHP version guide.

Step 6: wp-cron and the database

WordPress runs scheduled tasks (publishing, emails, cleanup) when people visit, through wp-cron. On a busy website, this adds work to every request; on a quiet one, tasks run late. The fix is a real cron job, set up from the panel; the WordPress example is in the cron jobs guide.

Over time, the database fills up with old post revisions, temporary data and tables left behind by deleted plugins. A regular cleanup, done after taking a backup, keeps it lean.

Step 7: only now, resources

If your images are optimized, your plugins are cleaned up, caching is on and PHP is up to date, and the website still slows down at traffic peaks, the plan may be too small for it. The classic sign: everything runs smoothly at night and struggles exactly when most visitors arrive. The differences between plans are explained in shared hosting, cloud or VPS.

If you'd like someone else to handle updates and checks, with a backup before every change, see WordPress maintenance. And if your WordPress site is currently with another host and you'd like to try us, we'll move it for free, under the terms on that page.