[gfxmonk]

For stuff like tab completion and for launching small command-line apps (think "grep", "sed", etc), absolutely. A penalty of hundreds of milliseconds for the _launcher_ alone can double (or more) the total execution time.

I use zeroinstall a lot (I'm a contributor), and I turned off tab completion because the lag (of the python implementation) made me wonder if my terminal had locked up, which was far more distracting than trying to remember the available arguments. I have re-enabled it in the ocaml port, because now it's effectively instant.