I'm afraid neither of the tie examples, this one or the one above, compare very well in terms of performance with the seek solution:

Using tail module w/ tie: 0.200u 0.050s 0:00.32
First example w/ tie: 0.270u 0.030s 0:00.38
My example using seek: 0.030u 0.010s 0:00.07

I'm happy to have the examples though, just learned about tie tonight -- thanks.