dnf.conf: cleanup, reword fastestmirror comment and uncomment it

etc/dnf/dnf.conf

@@ -2,23 +2,16 @@
 gpgcheck=1
 # 3 is the default, increase this in case of kernel upgrade trouble (unrelated
 # to space, see dracut.conf.d for that)
-installonly_limit=3
+#installonly_limit=3
 clean_requirements_on_remove=True
 best=False
 skip_if_unavailable=True
 
-# Fedora 40
-# https://fedoraproject.org/wiki/Changes/Drop_Delta_RPMs
-# Consider `sudo dnf install python3-dnf-plugin-cow` instead on 40+ and CoW
-# filesystem (btrfs, maybe xfs (untested)). Fallback likely slows down ext4.
-# https://fedoraproject.org/wiki/Changes/RPMCoW
-deltarpm=False
-
-# Explicitly enable finding the fastest mirror
-# NOTE! This actually measures based on ping instead of available bandwitdh
-# and the Fedora infrastructure is already giving most suited mirrors, so
-# enabling this may lead to worse performance.
-#fastestmirror=true
+# Find the mirror with the lowest ping. While this might be the closest
+# mirror, this won't consider the available bandwidth which may result into
+# slower downloads than the order Fedora provides servers in when this is
+# disabled.
+fastestmirror=true
 
 # default 3, max 20, often suggested 10. I am not sure high numbers bring
 # benefit, but double seems fine