>>/704/
Hmm, not completely. There are some options under options->connection that limit how many network jobs can run at once, but that isn't really what you want.
The client's ideal has generally been to run all simultaneously and let the bandwidth rules slow things down, but there are some hardcoded limits, I think around about 10 or 15 file and gallery downloaders running at once, to stop some back-end things getting gummed up.
I could just expose those hardcoded options to you, probably on options->downloading, so you can set them as low as you like. I'll just say/warn that these limits are hacks that I put in an emergency because the system grew faster than my back-end could deal with it, so it is a bit ugly--downloaders that are blocked by this limit just sit there, no status updates, because they can't even boot to say they are paused. The whole system is pending a rewrite, but if you want to artificially limit, I can keep those options in the new system.