ADDENDUM 1
As Ashley points out, "Prefer to add the shader effect to a whole layer, then put any objects you want to have that effect on that layer. This means the overhead of processing a shader only happens once." Thus, I control the tint and brightness of other layers independently (per layer basis) using the Tint effect applied on a layer.
Unlike the Tint mask, Tint affects only the tinted object/layer (and does not affect background objects/layers). As a further optimization, be sure to keep the option "Force own texture" of non masked layers (simply tinted layers) off.
ADDENDUM 2
Anyway, Ashley, it would be very useful, for situations like this, to have a plugin which composits/blends chosen images/sprites in real-time (per tick basis) and gives them readily available as a single image/sprite object. Thus, we could elminate the overhead of using the transitory invisible layer (as is the case with Paster plugin) and would have a more elegant overall solution.