How Long Does It Take to Render a Web Site?

i've focused my concerns over performance into the back end, right? And so however long it takes to render h t m l bla, bla blois, and this comes primarily because my background's mostly ruby on rails. But now i'm thinking, ok, well, what if i put in, say, a stimulus jas or a react or a angular or something, right? How does that affect this? Right? Does does it kind of add up  including loading in whatever components i've put into my web site so that this thing shows up or doesn't, and including all the c s s? And does it also include the time it takes to go back