I must apologize, I keep forgetting that I am on broadband.
The updates are very small if done daily, and you may notice a little slow down as avast updates its' data.
Please remember, that it is still protecting your system even while it is updating itself, so a little minor slowdown for a few seconds is understandable.
If however, you do not wish to do so daily, I would at least check 3 times a week, beginning, middle, and end.
The updates may be a little bigger, but not much. The longer you put off checking for updates, the bigger the update may be. Also, it is just safer to keep up with them.
