Hi Sebastian

The thread above yours covers the topic. Also, transfers from sources at <1KB/s don't show decimals, but you can look in Tools->Statistics->Bandwidth->Downloads to see if the HTTP transfers are "stuck" or actually proceeding in fractions of KB/s.

If stuck--just kill the download, resume it from the Library page and search for new sources. If the same file can be found, it will resume where it left off.