I tried to replicate the issue without success so far, mostly because my connection is very fast ( 250 MBps ) so the download only takes two minutes. Cpu usage during that is around 45%.
The download size is 2.7 GB, so either it didn’t take 20-30 mins, either the average download rate is half lower than in your screenshot. Which makes even less sense, as the cpu should only get busy as it receives a chunk. So on a slower connection, the cpu should mostly be idle awaiting for the next chunk to be downloaded.
We’re keeping this issue in mind, however as you can imagine, it isn’t a very high priority at the moment.