> It would send 4 bytes while one would do... as I sayd a lot of those records would be sent back and forth between client and serves and to optimize for speed I want to make the size of one row as small as possible. I know it looks like a premature optimization but my past expierence is that pulling data from DB is the main bottleneck in the kind of app I'm creating.

You won't notice any performance difference even if your "a lot" has
9 zeros.

SY, SD.