Damn, I am late to my own party! Don't seem to be getting any notifications from the forum.
Anyhow, in this case, it turned out that the user's CPU was maxing out, being an old machine.
Another user appears to be experiencing the same or a similar issue on Reaper x64 and Windows 7 x64, and it is not the CPU this time.
I'll drill down to all possible causes and circle back here. Thanks, guys!
