Stylus and CoffeeScript middleware automatically compile any Stylus and CoffeeScript code for you without having to restart your app, eg you can edit a .styl file and just refresh the page in your browser and your changes will be there. I find this to be very convenient while developing, but would that severely effect the end-user's page load time in production?
My Express setup is usually something like this (CoffeeScript):
app = express()
app.set 'views', __dirname + '/views'
app.set 'view engine', 'jade'
compile = (str, path) -> return stylus(str).set 'filename', path
app.use stylus.middleware {
src: __dirname + '/stylus',
dest: __dirname + '/assets/css',
compile: compile
}
app.use coffee {
src: __dirname + '/coffee',
dest: __dirname + '/assets/js',
encodeSrc: false
}
app.use express.static __dirname + '/assets'
It will definitely be slower than serving the pre-compiled files statically (if Stylus and CoffeeScript don't support caching which I don't know). The question is, whether this matters. And this depends on the intensity of the traffic your app receives.
In general, I would suggest to pre-compile your files and serve it statically. For the deployment, I would suggest to use something like Gulp.js and watch your files. With gulp your files can be automatically compiled on file changes which is most of the time better than compiling it when the files are requested.