Gladly, I was able to devote some time to update yum fast downloader plugin to work much better with recent yum versions in Fedora 19/20. The plugin effectively disabled delta rpm support since the integration of presto into yum. To fix the issue, I reworked the plugin using the new download framework of yum/urlgrabber. The result is yum-fast-downloader plugin for Fedora 20, which not only fixes the problem but also brings better integration. As a result, the plugin is now responsible for almost all downloads including downloading drpm packages.
Besides, it is now possible to specify arbitrary command line arguments (e.g. -q) for aria2c in the plugin’s configuration file. Unlike previous versions, in this version download of multiple files in parallel are handled by multiple instances of aria2c; but I’d like to change it back to a single aria2c instance in future. I’ve added the new version for Fedora 20 in the repo, but not for Fedora 19. It should work on Fedora 19 too, but I have not tested it. If you tried YFD 0.6.0 in Fedora 19 successfully, please let me know so that I’ll add the new version to F19 repo too. Thanks!
What about DNF?
DNF looks promising. It is much faster than yum, and even uses xml metadata rather than sqlite ones which are smaller. However, it’s internal structure is completely different from yum, so it needs a completely new plugin. I’m still not sure if it is possible, but I’ll try in future. :)