Sure it does, and if we all do this it wastes the user’s memory.
The whole point of shared libraries (like gems) is that we all use the same ones.
A gem install progress bar was logged as an issue I think several years ago.
(I even attempted to write one.)
We could inform the user that it will take a few minutes to load the gem, … but that usually means a model messagebox, which does not make sense during SketchUp startup (where dependencies like gems are installed.)
So, … it takes a few minutes more the first time an extension loads and installs RubyZip. Thereafter it is no longer an issue.