Hello Sung,
how many routes are in your BGP table?
you can check this with
sh ip bgp sum
It is true that you only need to add one statement to configuration to make the change but the consequences of this are the following:
it triggers a recalculation of all BGP routes (it may happen at next BGP scan execution).
Then after BGP process proposes possible alternate paths these need to be installed in the IP routing table.
the CEF tables of the device nees to be updated too.
Again all this should cause just a peak in cpu usage and some more memory usage.
However, specially if the number of BGP IP prefixes is high I would ask a maintanance window for safety.
Hope to help
Giuseppe