Slow start of the CLJS repl using shadow-cljs on Windows

[dabrazhe]

This is measured on Windows 10, HP, i5 2.3 Ghz 8 GB RAM.

Using Shadow-cljs on a basic cljs project. Here are my measurements and notes from the work PC:

fetch metadata and extract:shadow-cljs => takes a little while
npx: installed 90 in 41.514s  => it's quite long, why should it install it every time?
[:app] Configuring build. => takes a while, not sure how
compiling the app => about 10-15 seconds

I am comparing Jack-in with Cursive, where I need to

• start the shadow-cljs server (the catch is that it's almost always already been started), if not it takes about 0.5 minutes
• start the clj repl
• issue the shadow's node command to start the node REPL

Alles zusammen, it takes Cursive

• about 10 seconds to give me the node-repl when the shadow server is running and
• 35-50 seconds when I have to start the server (and no dependencies has changed).

Which is quite a difference when I am trying to use Calva, and cannot keep all apps open all the time.

[bpringe]

npx: installed 90 in 41.514s => it's quite long, why should it install it every time?

npx only temporarily installs the package and then removes it after use. This ensures the latest version is used each time it's run with npx. https://nodejs.dev/learn/the-npx-nodejs-package-runner#installation-less-command-execution

I think the reason it's faster in your Cursive example is because:

• You started the shadow-cljs server first
• I'm assuming you're not using npx, which means no installation of shadow-cljs

You could globally install the shadow-cljs cli, start the server yourself (no installation thereafter each time you start it), then run the Calva command to connect to it - "Connect to a running repl server in project..."