Since this is not the first time this issue pops up maybe it's worth adding stuff like this to a FAQ (no one reads later )
Quite a few programs really suffer from slow random IO -- especially writes (not only this downloader stuff but also browsers like Firefox that have many SQlite databases open and try to write to them in 32K chunks or even whole 'operating systems' like Android). And since users tend to try out new OS images with crappy SD cards lying around their first experience with Armbian might be 'Huh? Internet slow as hell! Armbian sucks!' (blaming software for 100 percent hardware related problems)
Icarus reacted to tkaiser in Orange Pi One - Slow download speed in web browser, fine in wget