Not likely. You would only get a lag if the wireless users were using too much of your internet connection and it does not matter which they use. Actually which ever works WORSE for them cause them to use less of the internet connection.
There could be some strange issue if you transfer huge amounts of data between wireless machines that you could exceed cpu limits due to encryption overhead but it is highly unlikely. This would only occur if for example you were streaming multiple uncompressed blueray streams to multiple devices all within your house.