I also let $GPGGA though the filter. These settings will make S&T work pretty good, but I think I still notice a minor delay (maybe half a second or less), but is totally usable and the lag is very very small. Hope these findings will help other people trying to make a 5hz receiver work with S&T.
Theory B Let's assume it is something else that triggers the 5Hz mode, and we simply want to reduce the amount of data.
1. Remove the Virtual Port you currently have.
2. Add "Virtual COM Port / NMEA Filter"
3. Select the COm port number you want to create and click "OK"
4. Now a "NMEA Filter" dialog shows up, and here we can filter the data stream.
5. Click "block everything but..."
6. Select "$GPRMC" in "Command filter". Set "Time interval" to 1 (second)
7. Click "Save"
8. Repeat 6 & 7 for "$GPGSA" and "$GPGSV".
You should now have a list of filters in the list box under the "Save" button.
9. Click OK on the dialog.