Lump sum overpayment of mortgage - options

[The_Doc]

What do people think is best?

I have recently overpaid 8% of my mortgage with cash.
Term left is 19yrs.
There is no way I will be going at it this long, I will pay it off in 10 most likely.

Should I:
a) keep term at 19 yrs and ask for reduced monthlies, put monthly money difference into something more rewarding
b) reduce the term.

Which is financially more efficient? Apparently I get to pick.
Its fixed at 3.98% for another 3yrs. (of a 5yr fix)
I pay my monthly easily each month with (fortunately) money to spare.

[Jawls]

A) is more efficient, provided that you put the difference between your prior payment and your new payment into savings/investments that return more than your mortgage rate of interest. Without that alternative investment B is more efficient.

Of course, if you have a savings/investments option that returns more than your mortgage rate of interest, then your initial overpayment wasn t financially efficient in the first place. But no use crying over spilt milk.

(Also, there are other factors at play aside from financial efficiency, but that s what you asked about)