Have you read the fine print in your service's Terms of Service?

Some firms -- mostly those catering to relatively low demand useage, like family web sites -- have astonishingly tight restrictions on transfers, simultaneous sessions and the like.

And you may also be well served to compare the ways FileZilla handles multiple transfers, as variation between FZ's and Net::FTP::Simple's methods might be useful

Or, of course, this may be entirely irrelevant, but one can hope it might be some help.