Description of problem:
Command 
dnf -y repository-packages MYREPO upgrade
is VERY SLOW (more than 5mins)

Version-Release number of selected component (if applicable):
Fedora Workstation 22 x86_64 (latest updates)
dnf-1.1.0-2.fc22.noarch


How reproducible:
dnf -y repository-packages MYREPO upgrade

Steps to Reproduce:
1.
2.
3.

Actual results:
Upgrade with DNF takes more than 5 minutes.

Expected results:
Upgrade takes less than minute.

Additional info:
I have problem while trying to update only installed packages from specific repository with dnf.
I use following on Fedora 22 x86_64 with dnf-1.1.0-2.fc22.noarch:

dnf -y repository-packages MYREPO upgrade
Upgrade is successfull, but it takes VERY LONG time to complete (5mins).


If I use following:
dnf -y --disablerepo=\* --enablerepo=MYREPO upgrade

Upgrade fails with:
Skipping packages with broken dependencies:
Because I have one package on MYREPO that requires (have dependency) package from other repo (fedora repo).

Yum command worked fine, but its deprecated.
yum-deprecated -y repository-packages MYREPO update

Earlier version of DNF (maybe few weeks ago), throw these messages while doing upgrade:
Package SOMEPACKAGE1 not installed, cannot update it
Package SOMEPACKAGE2 not installed, cannot update it
Package SOMEPACKAGE3 not installed, cannot update it
Package SOMEPACKAGE4 not installed, cannot update it


I assume that the problem could be in the fact that DNF is trying to update ALL packages from my custom repository MYREPO, but on my PC, I use only few of those packages (have installed just a few packages).

Note: Those custom packages are added while building Fedora ISO with pungi.
Command 
dnf list installed
Lists all installed packages as from repo @System