> would never describe it as snappy. The entire thing is single threaded so the UI locks up at the slightest provocation
This part seems to be about the User eXperience. (which I agree with, but elisp can start child processes and wait for the results asynchronously, so this is the fault of whoever wrote the code https://www.gnu.org/software/emacs/manual/html_node/elisp/Ou... )
