Since I've just started F@H, I have found this option under "Connection."
It was not check in the box prior when F@H was installed. So, out of being curious on the last WU completed, I checked the box to see what would happen.
Well, the good news is, the new WU is 250 frames vs. the 1500 frames.

However, it seems that it takes a little longer to chomp the frames in the 250.

The best news is, it's almost double the points.

Then after 1-hour the number of days to crunch went from 389 days down to 3 days.

So, with almost an extra half day more to crunch a WU, I'm getting almost 200 more points per WU. I'm very happy now.
I wonder if this option is used for turning on for high speed internet vs. the 5Mb limit for dial-up folding users? Any comments?