fix zle lag

[mcandre]

zle takes so long to finish loading that up arrow corrupts to low level "^[[A" character sequences on screen in new terminal tabs.

zle seems to load just before the prompt. If I wait until I see the prompt appear, then the key processes successfully. But that's such a pain, when opening and closing tabs a thousand times a day.

[mcandre]

... do we dump zsh in favor of mksh?

[mcandre]

... do we dump iTerm2 in favor of other terminal emulators?

[mcandre]

Problem reproducible in iTerm2 with NO zsh user configuration.

Apple Terminal also has this glitch, though the frequency seems significantly lower.

iTerm2 has additional other visual glitches and lag. Curious.