iTerm开启新tab或第一启动时，需要很长时间才能显示到提示符。搜索一番后，是由于login程序需要显示last login时间，就在/private/var/log/asl/查询这些文件，为了加快速度可以直接略过。方法如下：

iTerm

Go to iTerm > Preferences > Profiles > Default (or the profile you use) > Command
The radio button should have Login Shell selected.
Change it and select Command:.
On the text box on the right, type:
/usr/bin/login -pfq [YourLoginName]

Terminal

Go to Terminal > Preferences > Profiles > Shell > Startup
Select Run command:
On the text field type,
login -pfq [YourLoginName]
Uncheck Run inside shell

Reference:

https://www.reddit.com/r/applehelp_betas/comments/3jzzyp/slow_terminal_or_iterm_start_times_on_el_capitan/