Has your friend tried disabling their firewall, or making an exception for D:OS? Firewalls have been known to cause long load times (in general they should shut down all non-essential programs before starting the game). Unless the system is near or below the minimum specifications, 5 minutes seems a little long. They can check that in a single player game, if they don't want to do so when online.
The problem with the stats is a known issue that is currently being looked into, but so far has been difficult to reliably reproduce. Usually people with this problem have found that just reloading the save, perhaps multiple times, will get it to work.
More information about both systems may be useful. Email supportdos@larian.com, and I'll add that and your description above to the bug report for this issue.
For Windows you can use the
D:OS support tool to generate a report.zip file, which will contain system and game information, as well as your saved games. To reduce the file size, the host can delete all but one save from the zip, and the client all saves (if they also have a single player game going, for example).
For Mac, I don't know if Yosemite moved anything around, but to get system specs in Mavericks you can use 'system report' from the 'about this mac' apple menu item or the 'system information' app (utilities folder); in earlier versions use 'System Profiler'.
Saves are in a folder something like:
~/Documents/Larian Studios/Divinity Original Sin/PlayerProfiles/<ProfileName>/Savegames