There are steps that can be taken to make sure your site is performing optimally. Improvements can always be made.
As an example: Someone who has a WordPress site might think that there is nothing they can do to increase performance. Their site performance is-what-it-is. Nothing could be further from the truth! A short list of actions to be taken follows:
When you first decide that you are going to create a WordPress site, take time to find a theme that performs well. In this case, reviews are your best friend.
One of the quickest and easiest things you can do is to use a Content Delivery Network (CDN). A CDN allows you to move your static assets (images, .css, .js…etc.) to another site which is optimized to deliver that content, and the CDN also can deliver those assets from a server that is close to the requester. This is very easy to configure in WordPress and will give you an immediate boost. My experience has been with MaxCDN.
There are plugins that have been created to address performance optimization. One that I have used is WP Rocket. This gives you the ability to implement a LOT of performance improvements by selecting checkboxes. Note: be careful with some of the options and I would suggest selecting them one-by-one (and validating that they give you what you want without breaking your site, before moving on to the next).
Also, there are plugins that optimize images (shrink them losslessly).
My advice is to experiment with these plugins and check your speed and functionality after each one is implemented.