It seems that the yum command is capable of performing a package search even while there is a package installation going on in the background.
In contrast, trying the same with pkcon would make pkcon idle until the installation is finished, before the search will run.
Is this correct and if so, can it be improved to be on par with yum itself?
In general, PK cannot do actions in parallel. That said, code exists in the daemon to do this, although the way the yum backend is structured disallows this. I hope that in the future with the zif shim code we can do our own access of the yum data and get rid of this artificial limitation.
We moved the upstream bugtracker to GitHub a long time ago. If this issue still affects you please re-create the issue here: https://github.com/hughsie/PackageKit/issues
Sorry for the impersonal message, and fingers crossed your issue no longer happens. Thanks.