One of the most common file types that unnecessarily lengthens page render times are jQuery files. Whilst they can add fancy effects like animation, the cost in loading time can sometimes out-weigh this, or not actually come into effect in the above-the-fold content. If this is the case, it is best to defer loading the jQuery file until after the page loads. This is changed in the page’s HTML, and there are lots of plugin options that can help you with this (we will cover a few below).
Alternatively, instead of deferring the loading, you can consider loading your files asynchronously. There are some differences between the way the two processes work, and it is worth reading through this article from Kinsta which explains the differences if you are interested in this other option.