I got bored and usually dont care much about "benchmarks".
Every flash was without any additonal apps. Just antutu. 1 cycle.
PACMAN ROM was milestone 1 (17/06/2014)
KitKat ROM was nameless (21/06/14)
While PACMAN ROM could be compared to less-lag variant of the ICS Stock ROM, with many, many(!) options,
the nameless KitKat ROM is nearly lag free and very fast ! (apps, gaming, taking photos etc.)
Hence I cant explain the huge difference between Gingerbread and KitKat. (except that kitakt ROM is an early test version)
Also keep in mind that Antutu v2.3.7 is from 2012 and the Optimus 3D is from 2011.