There can be a slight delay when changing frames or groups. I think it would be less that a second. More like the delay between 2 fine moves.
Are there any WAIT statements or code that iterates (loops) a lot?
No waits no calculations. I jumped them deliberately to check if this was the case. The delay is still the same and the only difference is that from a single Group Mask program I call a Group Mask 1,2 program. Everything else is the same. Also the delay is the same when exiting the subroutine. One other thing to note is that on group 2 (servo gripper) the Continuous Rotation function is enabled. I don't know if by entering a program with a motion group that uses Continuous Rotation function the motion planner does any magic to calculate or store a zero value for that axis.