32 bit (actually 24 bit) colors = 2^24 = 16,777,216 colors
16 bit (actually 12 bit) colors = 2^12 = 4,096 colors
It’s not “half” the colors, but 4,096 times more colors. The 16 bit colors option comes from … like 1990.
It’s nice, if it helps you, but you could also remove effects or lower (effective) resolution.
[ Edit ]
just remembered, that this is the suggestion section … better move to PhP.
(edited by Nretep.2564)