You can use Google's Pagespeed Insights to check the speed of your site and then it will give you recommendations as to what is loading slow and why. Then you can take a call on what kind of a website you have and how you can make it even better basis the platform and hosting.
I think ads and unoptimised images are the two biggest culprits why some sites either hang or load incredibly slowly. For the former reason, display advertising is undeniably effective in monetizing high-traffic websites. However, this should not come at the expense of performance or user experience. Allowing too much advertising to slow down your website is a bad idea! The increase of HTTP requests is the most evident effect of overloading your website with adverts. For the latter, While loading, high-resolution photographs might require a lot of bandwidth. Uploading bigger photos and then scaling them down might increase the size of your web page needlessly, making it difficult to load.