Take the following example that I've tacked to the end of test program:
I'm thinking hubexec and cogexec will take exactly the same number of sysclock cycles per loop because instruction fetching triggers a fifo refill while the WAITX is still executing.
Any long executing instruction at the end of the loop will benefit from this. Possibly even a RDLONG although there may be congestion on that one. Admittedly, most are going to be waiting type instructions but a cordic command can take advantage of it.