I had a little time today to go through some of the blogs I read and Lee Brimelow wrote on The Flash Blog that a Boolean takes up 4 bytes (confirmed by the Flash player team). Initially, in his article he wrote about one byte being occupied by a Boolean but he updated it later on.

While I understand having a Boolean occupy 1 byte (guess that would be a minimum size for objects), I think having 4 bytes for a Boolean is a little too much. Especially since a Boolean value can only have two values (true/false – 0/1) so it would only need a single bit. In this case, 10 Booleans would take up to 40 bytes. Now, for the great majority of Flash apps this isn’t really a problem but for those who need to keep their apps to a VERY VERY minimal, that space could count, or in case when high speed is needed.

The conclusion: don’t use too many Booleans if you don’t have to or use Lee’s method of to handle more Boolean values (a good one I might add), by using ByteArrays.