Hlo Friends,
Can you tell me, What methods should apply to decreasing the loading time of a website?

You can use Minimum images, decrease the file size of the images that you will use help to Decrease the loading time of a website.

Top 10 things you can do to speed up your site
    Minimize HTTP Requests.
    Reduce server response time.
    Enable CSS compression
    Enable browser caching
    Minify JS
    Optimize images.
    Optimize CSS Delivery
    Prioritize above-the-fold content.