I don't know who told you that but lite-C is way faster than C-Script. You can try this with a little loop

while (i < 100) {
while (j < 100) {
while (k < 100) {
k += 1; }
j += 1; }
i += 1; }

In most cases speed advantage is not this visible because the engine functions are the same under lite-C or C-Script, but when using only calculations and not calling engine functions, lite-C speed is impressively faster.