Optimizing WordPress can greatly improve its performance by making it run more efficiently. Here are some factors which influence the performance of a WordPress site –
Enabling caching is probably the simplest and easiest way to improve any WordPress site’s performance instantly as it reduces the number of queries made to your WordPress database.
You can have a look at all the important factors which influence WordPress performance and some of the steps you can take to optimize it in this support article.
To learn how to optimize WordPress to load in less than one second, check out this article by Online Media Masters (non-technical) and this one by Toptal.