If you see that the demo import process is taking forever or it's not completed correctly this means your hosting PHP.ini limits are too low for working with WordPress Importer and demo data can not be imported on your server without the right configuration.
Change your PHP.ini settings according to the following minimum values. If you don't have access contact your web host and ask to have the limits increased.
300 (600 recommended)
Those settings are required to successfully import all demo content and images.
Check this official WordPress article on how to increase memory limits for your WP:
Cheap or bad shared hosting may not allow you to use these values (in this case you won't be able to import demo data onto your server). You need to switch to another hosting.
Your server is too slow to install plugins and import data demo content at the same time. To resolve this issue I recommend you should:
First, install all the required plugins for your site like:
Nasa Core - Add some theme featured (Required)
WooCommerce - WordPress eCommerce plugin (Required)
WPBakery Pages Builder (Visual Composer) - Used for page builder (Recommend)
Elementor Used for page builder (Recommend)
Revolution Slider - Used for main Sliders (Optional)
Contact Form 7 - Used for contact form and newsletter signup (Optional)
Elementor - Header, Footer & Blocks (install if you use the Elementor plugin to build pages)
YITH WooCommerce Compare - Compare functional products (Optional)
Second, proceed to import Elessi data demo content with any pages that you want: