Slightly offtopic: many commenters lament that latex is slow. I switched to https://tectonic-typesetting.github.io/en-US/ which is very fast and have better error reporting.
This is something which I have found can affect initial first time document builds since it can cause sequential downloading of a lot of small files sequentially.
The reason why it is difficult to parallelize or fix in tectonic itself is the way latex itself is parsed in a turing complete fashion. Importing a package can affect subsequent parsing. This makes it basically impossible to build a map of package dependencies without interpreting the entire document.
I'm curious to see how typst handles such things.