If your website pages are taking too long to load up to the screen then you may need to review the images you are using.
A common factor that causes websites to slow down when loading is related to the images on your website. High resolution images that are a large file size take longer to load on slow internet connections or on mobile devices with a poor internet signal. Image file size should ideally be below 100kb.
To help resolve this problem there are various on-line tools https://www.websiteplanet.com/webtools/imagecompressor/, http://compressjpeg.com and https://tinypng.com to help you compress your image to a smaller file size.
Ideally, your images should be formatted to jpeg or PNG format.
To check the speed of your website in desktop and mobile versions visit https://developers.google.com/speed/pagespeed/insights/ and enter your website address, it will analyse your site and provide a detailed report, letting you know what needs to be fixed to improve your website speed.