If you're worried about performance hit you can do the same thing in the Construction Set yourself. Myself, I stopped using Fundament for this purpose years ago (nowadays I only use it when I want to use Willful Resistance or NGCD (which I prefer over Realistic Leveling)).
My personal Fundament substitute adjusts the rate gain of most skills, changes several skill-attribute affiliations, adds the ability to gain some experience from missed ranged spells, and raises the total number of skills needed to gain a character level from 10 to 30, which has the dual effect of slowing down the speed of character leveling by about 1/3 and ensuring that my characters usually receives +5 Attribute bonuses.
It is very easy to do and it needs no scripting whatsoever.
I thought something seemed very familiar about all this. But, then, you know, Gade, when you've written 30,000 posts in a gaming forum such as this you're bound to repeat yourself sooner or later. I do have to admit that I had the strangest feeling that this had all happened to me before. But, then, you know, Gade, when you've written 30,000 posts in a gaming forum such as this you're bound to repeat yourself sooner or later.