CIDER slows down Leiningen startup. Here is how to fix that.

Official CIDER documentation recommends putting CIDER into user's profile.

{:user {:plugins [[cider/cider-nrepl "0.9.1"]]}}

If you don't need to have it available all the time, but only when you run lein repl, you can move it into :repl profile.

{:repl {:plugins [[cider/cider-nrepl "0.9.1"]]}}

After this, startup time of non-REPL tasks will be much faster (e.g. 2 seconds vs 8 seconds for `lein help` on my machine).