SymptomsThe container backup process runs very slow. Especially the state "Backing up additional data" takes much time.
CauseAn old version of zip.exe tool is shipped with Parallels Containers.
ResolutionTo work the issue around it is necessary to replace zip.exe file by later version (2.32 or later).
Parallels Containers 4.5:
The file is located in "C:\Program Files\Parallels\Containers\bin" folder on x86 server and "C:\Program Files (x86)\Parallels\Containers\bin" on x64.
Parallels Containers 3.5.1 and 4.0:
The file is located in "C:\Program Files\SWsoft\Virtuozzo\bin" folder on x86 server and "C:\Program Files (x86)\SWsoft\Virtuozzo\bin" on x64.