Looks pretty nice so far. I'm left wondering though, what's causing the drops in frame rate? Only thing I can think of is that you are trying to use the occlusion? As far as I know it, it will always cause frame rates to hit rock bottom, no matter how much you tweake it.
The original was ENB was added to the mod by me, it never was perfect but the settings where left at values not too heavy for most of the lower end systems still being used by discovery members.
that was a requirment of it being allowed to be released with the mod, aswell as the option of actually installing it or not.
There is no reason not to upgrade it to a later version of ENB though, the one we have now is basic in comparison to some of the newer ones. The pallet texture is one of the main things missing from it.
Reason why i've not bothered with it is really because of the work being done with Freeworlds, that will basically make the ENBSeries mod obsolete, if it's ever released to the public, and it's to my understanding it will be eventually.