What is the easiest way to learn CodeIgniter?

Def' Ci4, Laravel is too heavy, too slow in loading times (which matters if your client has crap connection or a lot of merch). Also it seems like to use Laravel I have to spend too much time to learn it - time that can be spent learning PHP, JavaScript (not just syntax, but best practices, and principles like OOP, REST, new features, etc.).

- CI is simple, robust, flexible. Very minimal, but still with a solid enough structure, and security. Adding new features and realizing your clients' random requests is fast and easy.

- Laravel has a lot of stuff available for it. Does not seem like it is good enough for SEO unless you commit the time to actually optimize it.

Easiest way to learn any framework is to build a controller with some methods (pages) and then keep building. Looking at forum for examples/ideas.
P.S. this is CI forum so of course a lot of people are going to say CI is better.

You can see things I made with codeigniter here: itart.pro its not overly impressive as I have very little time to learn.