What are the best ways to get content to load faster? [on hold]

I know this is one of those questions that someone will say: "this is the type of question that will invite stupid people to flame each other," but hear me out:

I'm fairly new to javascript, having done most of my programming many years ago, but here goes...

I've seen several benchmarks of different frontend frameworks, most recently this one (https://markojs.com/) that claims to be small, efficient, and fast compared to others.

I mostly want to do interactive data visualizations that are fun and informative. I'm a retired chemistry teacher and I like science stuff. It is important to me that the design is usable and valuable from the point of view of visitors. Personally, I want it to be beautiful and efficient as well. I guess I'll always be a teacher at heart.

From looking around, it seems like I should be using python (more familiar to me than R) and plot.ly, D3, or some library (another question I have!!! which charting library??).

I don't know how to use any of the javascript frameworks yet so it is difficult to evaluate them. A lot of the information I find is biased and subjective. From a design standpoint, which one can best help me adjust the look, feel, and function of my creations.

It doesn't matter how difficult it is: I can do it. Learning curve isn't a factor: I have plenty of time (I'm retired). I definitely want open source: it aligns with my goals.

I just don't want to mess around doing the wrong thing for a while before realizing the best way. I want to pick one and go with it. So ... what is the best way to tell? I'm a little stuck.