On dixie, I generally used zsh, but have been using bash on alice, since that's what I use at work. On the other hand, while zsh is _so_ big, I could never expect it to be fast, on alice, I find that opening a new shell takes irksomely long.
Tests: (avg m:ss reported by GNU time -v) -bash: no profile, no completion = avg 0:00.01 with profile, no completion = avg 0.00.10 no profile, with completion = avg 0:01.16 with profile, with completion = avg 0.01.27 -dash: no profile = avg 0.00.00 # to fast to be timed?; highest was 0:00.03 with profile = avg 0.00.08
Ok, so maybe an Atom based netbook isn't as powerful as a server with multiple quad core Xeons but that is still a rather big difference. No wonder though—on alice, /etc/bash_completion is 1700 lines and /etc/bash_completion.d contains over 25,000 lines of scripts to source.
My shell profile only adds like 700 lines of code when run on Linux. Although zsh really made me appreciate context-sensitive tab completion, the only interest I have with it in bash, is pretty much for git.