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ZSH takes about a second and a half from creating a new terminal window to being ready. I'm pretty sure that the culprit is compinit.
I haven't been able to find good documentation on compinit, but it looks like it should be caching all of the necessary things in some file like .zcompdump.
Any tricks on speeding it up?
oh-my-zsh was taking about 1.5 seconds to start up on my laptop. I wrote up some of the steps I took to get that down to about 0.25 seconds.
Another kind soul summarized the steps required to integrate my changes into your copy of oh-my-zsh.
The biggest problem is that compinit was being called a whole bunch of extra times instead of just one time after the fpath was completely defined. I made those changes on my branch of oh-my-zsh on github. The changes have been discussed on github and they seem to be working well for a few people. Hopefully the changes will be merged into oh-my-zsh in the near future.
While ZSH has it's own fair-share of slowdowns, if you find the terminal window blank for a few moments before you see the Last Login: line, you are going to need to clear your log files to see speed improvements. This is still an issue as of OSX Lion and will need to be done every several months. Lame, I know.
The command is:
sudo rm -rf /private/var/log/asl/*.asl
Of course, you need to read this article beforehand and so you know exactly what is going on, because running anything that says sudo rm needs to be thought about. I only put this here because your use of ZSH proves your competence with the command line to start.
-r since no directories are involved and it sn't needed. Omitting it leads to less tears if someone types sudo rm -rf / private/var/log/asl*.asl (space before private) by mistake.
cd /private/var/log/asl then rm -f *.asl. Also for the record, this answer saved me from a startup time that was approaching 10 seconds, thanks a lot!
May 12, 2016 at 22:19
trash /private/var/log/asl*.asl. trash will need to be installed, of course. brew install trash
In my case, NVM was making it slow.
Original code (at .bash_profile, .zshrc loads my bash_profile)
export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh" # This loads nvm
[ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion" # This loads nvm bash_completion
I've changed it to:
export NVM_DIR="$HOME/.nvm"
#[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh" # This loads nvm
[ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion" # This loads nvm bash_completion
alias nvm="unalias nvm; [ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh"; nvm $@"
Added the alias (last line), so I will only load NVM when I try to use it. It decreased the load time from 1.5 to 0.2 seconds.
/usr/bin/time zsh -i -c exit #If you want to time yours
My biggest improvement has come from removing items from the plugin=() section. The 'github' and 'brew' plugins are very slow to load.
I also removed hub which I had aliased togitand that sped up the prompt as well.
I've been using '/usr/bin/time zsh -i -c exit' to record the startup times, however compinit doesn't appear to make a big enough difference for me.
It'd be great to hear what others are doing to speed it up.
github and brew plugins solved my problem immediately.
Nov 15, 2011 at 3:02
git and brew plugins are quite essential to me. By removing ruby plugin solved my problem. Thanks.
Mar 19, 2012 at 17:30
Are you using the pre-installed /bin/zsh or another one? I ask, because
the zsh I have installed through fink starts terribly slow due its inclusion of zsh templates, while the vanilla starts right up.
Does running with an explicit dumpfile (compinit -d dumpfile) make it go faster?
The man page states that
The next invocation of compinit will read the dumped file instead of performing a full initialization.
compinit is never called. When I manually call compinit it takes a little while. Maybe it's just because Oh My Zsh adds so many bindings to compinit?
Zsh on its own starts up in around 0.1 second for me, which is plenty good enough. I just noticed as I got near the 50,000 command history mark that it became more like 3 seconds to load up the first prompt.
I dunno how you guys are finding all these other reasons for slow startup, but mine was exactly what my first guess was. I did a mv ~/.zsh_history zsh_history_backup and bam, 3 second startup is now 0.1 second startup. Curiously, /usr/bin/time /bin/zsh -i -c exit fails to capture the time it takes to load in the history.
If you don't have tens of thousands of commands in your zsh history, though, then this isn't it. My ~/.zsh_history measured 1.8MB. Its very possible to accidentally paste a large chunk of stuff as a command into a terminal, this will also bloat history up right quick (though this is something very much to avoid doing as it can obviously be extremely destructive).
Now oh-my-zsh checks special git configuration option oh-my-zsh.hide-status before querying status. So run
git config oh-my-zsh.hide-status 1
on problematic repository.
.zshrc. I am currently facing issues with slow internet response, which made zsh slow
Aug 12, 2016 at 2:02
I was using the theme "af-magic"
Switching to "muse" solved the issue.
Edit ~/.zshrc and modify that line:
#ZSH_THEME="random"
#ZSH_THEME="af-magic"
ZSH_THEME="muse"
These are the steps which I have used to optimize my shell startup speed and reducing lag in executing commands -
Powerlevel10k is a theme for Zsh. It emphasizes speed, flexibility and out-of-the-box experience. It is a reimplementation of the popular Powerlevel9k zsh theme. It looks exactly the same given the same configuration but renders prompt 10-100 times faster. It's optimized on every level of the stack, all the way down to using a patched version of libgit2 that can scan a repo 4 times faster than the original. It can remove Zsh startup lag even if it's not caused by a theme with features such as Instant Prompt.
login -pfq username /usr/local/bin/zsh -il
You wouldn't see the last login time printed when starting a new tab now. If zsh is not present in the location /usr/local/bin/zsh, you will need to install zsh using brew. The default zsh provided by mac is at /usr/bin/zsh and might be using an older version like 5.2 which can cause slow speed when used with iTerm or oh-my-zsh.
mkdir -p $ZSH_CUSTOM/lib && touch $ZSH_CUSTOM/lib/misc.zsh
mkdir -p .hushlogin
I added zmodload zsh/zprof to start and zprof to end of my ~/.zshrc file. Then I ran exec zsh to reload session. It turned out is_update_available was taking 95% of load time. I disabled auto-update by DISABLE_AUTO_UPDATE="true" in my .zshrc file. Then ran exec zsh and my problem was solved
zsh from source. Disabling auto-update did the trick as well.
I have really great speed improvements after clearing ~/.oh-my-zsh/plugins/ directory. There was many unused plugins inside it.
Add the following to your ~/.zshenv
skip_global_compinit=1
Many of the above answers are either:
I found a great article from 2020 by mjclemente that helped me to use plugins such as evalcache and zsh-nvm to speed up shell load time from ~1.65s to 0.6s without disabling any plugins: Speeding Up My Shell (Oh My Zsh)
Hope it helps someone else!
I stupidly had this line.
# pyenv
echo 'eval "$(pyenv init --path)"' >> ~/.zprofile
So it got slower and slower every time I opened a new terminal Tab.
I had 76 times that line in .zprofile 🤦
echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> /Users/aidanlister/.zprofile in my .zshrc. My .zprofile had thousands of lines of that in it. I deleted all but the first line from .zprofile, and commented out the offending line in my .zshrc, and now my terminal is fast again!