Hi,
You seem to be creating new Photo objects with every iteration ...
Instead of recreating the $buttonImage = $mw->Photo(-data => $data, -format => 'jpeg');,
you can opt for using the configure method on it ...
You also do not need to use the Button, a Label suffices.

...
use Tk;
use Tk::JPEG;
...
my $mw = MainWindow->new();
my $image = $mw->Photo();
$mw->Label( -image=>$image )->pack;
...
sub update_image {
...
 $image->configure( -format => 'jpeg', -data => $data );
 $mw->update;
...
}
[download]

regards,
johanvdb