What update are you talking about ?
Program Updates can be set to Ask when an update is available, or could be set to Manual, but these aren't that frequent.
Virus Definitions are more frequent (2 or 3 a day occasionally more), but shouldn't really have a great impact. These can also be set to Ask when an update is available, or could be set to Manual.
Streaming updates (very low impact a few KB each) however won't happen unless the Virus definitions are set to automatic.
So if you can give details of the problem ?