Lrdfrx - Yes, that's true, it can run heavier than some other download managers (although still nothing compared to a conventional interactive software app).
I typically close it, the second I'm done with it, due to the resources.
Ultimately, I think it's like anything else -- if you want the extra features/functionality, you have to contend with added resources. jDownloader is extremely powerful for a download manager. There are much easier options, but nothing anywhere near as robust. Especially if you invest the time to get familiar with writing rules or organizing your Usage Rules across multiple hosters, etc, etc.