I currently use coffeescript to write node.js programs and use them directly on the server.
Is there any loss of performance when I do this, is it useful?
coffee -cWould it be better to compile it into js files?
There is no loss, compilation only occurs when a file is loaded for the first time, because the Node.js program usually runs for a long time, so it can be ignored.
And usually you only need to compile the part of the code you write. Libraries on npm are usually compiled into JS, so the amount of compilation is very small.