In SDKManager all packages needs to be downloaded. The download is slow, so I tried to download at night.
However, it stopped working, and appears even slower to not working during night times of the US. That are hour morning business days. It is now 14-15 CET, and seems to have downloaded in 15 minutes. That is the first time, as it takes normally a day with 1 or 2 interruptions.
I have 100 Mb/s up and downstream and work with a UTP cable.
Maybe you can improve the download performance at any time.