If your site was recently loading faster, then a recent change may have affected the load speed. If this is the case, you can undo the change and see if that helps the site load faster. If you aren't sure what caused the slowdown, you can disable the various features of your site and add them back until the problem occurs again.
The following are some of the most common features that can increase latency.
Each plugin that you add to a WordPress site can increase the latency of the site. You can activate and deactivate the the plugins on your site to see if it improves the load time. For more information on activating and deactivating WordPress plugins, see Activating and deactivating plugins in WordPress.
The coding of a WordPress theme can also contribute to site latency, particularly when using a third-party theme. To see if your theme is slowing your site down, try changing your theme. For more information on changing the theme, see Change a theme in WordPress.
The .htaccess file does not normally impact the speed of a website, but if something has been misconfigured then it can happen. Try disabling it by renaming it to something like 1.htaccess, .htaccess.bak, .htaccess_disabled. For assistance with FTP, see What is FTP?.
If this fixes the problem, you will need to edit your .htaccess file to correct the error. Otherwise, if you leave the original .htaccess file disabled, then you will need to reset the Permalinks on your wordPress site. For information on this please see instructions here: Fixing Permalink Issues with WordPress.
The content of your website can also affect the performance of your website. If the objects on a page are poorly optimized, then more data will be sent than what is required. For example, large images can take a long time to load over slower connections, and external sources may not be properly optimized.
Sometimes network issues can also increase the load times of a website. To test this, you need to try accessing the site from a different network.
To check for network latency, you can use a tool called traceroute. This traces the path from the computer to the server you are accessing. For assistance running traceroute on Windows, see Traceroutes on Windows. For assistance running traceroute on Mac OS X, see Performing a Traceroute in Mac OS X.
When reviewing traceroute, look at the time it takes each hop to complete. This number should be fairly consistent. Any extreme variations can indicate a network problem. Contact your Internet Service Provider for assistance reviewing the traceroute if needed.