I have transformed the curves using the MOVE command, the Gumball, and
the NUDGE method (i.e. Arrow Keys), as well as ROTATE 3-D.
One additional behavior that initially accompanied the slow performance was
that whenever I was working in a single view (such as the perspective
view), the interface would change to four views while it was performing the
transformation and then return to the single view when the transformation
was complete. This is not happening in the latest WIP, but I am still
experiencing the slow performance with this particular set of curves. The
"preview" of the move is displayed instantly, then the "spinning circle"
appears and the application chugs away for several minutes while it
calculates the move. Incidentally, when I use the MOVE command, I define
the the move by snapping to two arbitrary points on the line beneath the
set of curves.
It may also be worth mentioning that the transformation is occurring a
little more quickly in the latest WIP than it was previously. It now takes
about three minutes, instead of five.
I hope this helps, but if you are not experiencing any performance issues,
the problem may be due to something specific to my setup.