Hi, This issue as been reported by many users over the last many weeks. It appears there is a bug affecting apt and is exacerbated by the fact that many users are in a geographical location that do not notice the benefit of the CDN acceleration. Some users change there default source and have posted various methods to deal with the apt issue. Personally I use the official Deepin mirror in my sources list and take advantage of the intelligent mirror switching function by selecting my favorite mirror in the Deepin Control Center, which by the way is not the fastest one listed. I was able to update 5 systems in less than 30 minutes with the last major update we had, which is a big improvement from the results I experienced in January. Until the var lock issue is resolved I also disable Auto check update in Deepin Control Center, this does require a restart to stop the auto check process. I also regularly manually clean my repository cache of retrieved package files and daily manually resynchronize the package index files from there sources. While these steps have definitely helped with my apt issues, I still occasionally have to send the sigint signal in the Deepin Terminal.

Personally for me, the first update which requires 227MB download was a disaster. It took me hours to complete. Actually there are two things I notice:
1. the two arror circle and the following percentage may not work correctly. During one update, the percentage stays at 0% all the time, even the update was installed eventually.
2. During the downloading, I use netstat and notice while the source.list points to packages.deepin.com, the connection was actually to a Amazon EC2 server. I think deepin tries to choose server dynamically based on some information. However, that "automatic choice" may not give you the actual best one.

But anyhow, after update and reboot, everything works charmingly as of now.
Though xfce and mate desktop environment seems to be more stable then dde as a whole.