If you are using the WordPress Toolkit extension, it detects new installations performed through the Application Catalog (or Application Vault) and integrates them with WordPress Toolkit. For this reason, installation of WordPress on a site takes up to 20 seconds. If you want to avoid this, you can switch off automatic detection of new installations by the WordPress Toolkit.
To do this, add the following lines to the panel.ini file:
[ext-wp-toolkit] autoAttachApsInstances = off