Speed Up Oh-My-Zsh

Others
shell
Catalogue
  1. 1. Intro
  2. 2. Step 1: Benchmarking Current Performance
  3. 3. Step 2: Check What Slows It Down
  4. 4. Step 3: Remove the Unnecessary Parts
  5. 5. The End

Oh-my-zsh is becoming unbearably slow…

Here are some approaches to speed up it.

Intro

I’m not a computer science expert, so I always choose to bear with the small issues happing on my laptop. My personal as well as working laptops are all Mac. And I use iTerm2 and Oh-My-Zsh to replace the default Terminal. For the zsh theme, I recommend mrtazz.

One of the costs of using Oh-my-zsh is that the startup times are slow. That’s what everyone says.

But recently, I am getting more and more frustrated by the slow startup times. By searching online, I found this tutorial really helpful.

The following are the steps I took to improve my oh-my-zsh experience:

Step 1: Benchmarking Current Performance

Let’s measure how long it takes to start a new shell session:

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$ /usr/bin/time zsh -i -c exit
5.46 real         3.58 user         1.37 sys

5.5 seconds??? That is not good at all.

Step 2: Check What Slows It Down

Now, please pay attention. Run the following command in your Terminal, and take note of the portion where the output pauses a bit. 

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$ zsh -xv

For my case, I found the portion for setting hadoop & hive parameters, and also for setting up nvm tend to get stuck for a while.

Step 3: Remove the Unnecessary Parts

As I don’t need hadoop and nvm that often, I decided to prevent them from auto-loading during starting up zsh.

So I made the following changes in my ~/.zshrc file:

  • Comment out the Hadoop Hive exports commands
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#hadoop & hive
#export HADOOP_HOME=$(brew --prefix hadoop) # /usr/local/Cellar/hadoop/2.7.3/
#export HIVE_HOME=$(brew --prefix hive)/libexec
#export HCAT_HOME=$(brew --prefix hive)/libexec/hcatalog
#export HADOOP_COMMON_LIB_NATIVE_DIR=$HADOOP_HOME/lib/native
#export HADOOP_OPTS="-Djava.library.path=$HADOOP_HOME/lib/native"
  • Comment out the nvm loading command. Instead, create an alias for it so that I can easily load it when I need it.
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#nvm
export NVM_DIR="$HOME/.nvm"
#[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"  # This loads nvm
alias loadnvm='[ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh"'

The End

That’s all~ Now let’s quite the Terminal and reopen it.
Test the time again:

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$ /usr/bin/time zsh -i -c exit
0.48 real         0.25 user         0.15 sys

Yeah.