It seems that scp is sometimes very slow (unclear what causes it as it's
not always the same). Packing up the files with tar performs a lot
better in these situations. And copying the files to multiple hosts
in parallel additionally helps to reduce the time required for these
steps.
Using --overwrite and -h preserves existing symlinks (e.g. for the users
file in /etc/freeradius/3.0) and overwrites the target file instead.
The -m option ignores timestamps when extracting the files as some target
files will be newer than the source. Using -h when packing up files in
load-testconfig allows using symlinks in the test config dirs to files
on the host running the tests.
By using the ControlMaster and ControlPath options, existing SSH sessions
are reused (a session to each host is opened at the beginning of a test
run). Also, RC4 is used as encryption algorithm to further improve the
performance. These changes reduce the runtime by over 20%.
