After each run of the flash target haxelib creates a new process. But after closing the app the process is still working. After each run there can be tons of haxelib processes.
I suppose this is HaxeDevelop doesn’t kill the process properly.
Some of the lime/openfl commands never end - if you run them from a terminal it will run the app and keep a logger alive until you kill it, even if the app itself is closed.