If you change the .ini to 512 and 256 then that's the original fix.  If you want to try 1GB it would be 
memblock1=1024
memblock2=512
I wouldn't increase the 2nd memblock over 512, it seems to lead to some instability.  768 seems more stable than 1024 for memblock1 to me.  This fix shouldn't of had any impact on your fps, if anything it should lower it by a few frames as you are loading more assets at once.
Skyrim is the bane of the GTX780, I know, I have one as well and I'm wishing I wasn't so hasty in getting rid of my 7970 6GB.  I made a healthy profit off of it, but 3GB of VRAM is brutal.  The 780 is a good deal, but it should've had a 4GB-6GB of VRAM option like the 770 does(it has a 2 and 4GB variant).  Skyrim can't use more than 4 anyway, but it burns a whole through 3 with a, frankly absurd, quickness.  You're going to have to do some tweaking, and decide where you want your high res textures.  On NPC's or the environment?  You can not have both.  I choose NPC's, so I have 4k bodies, armors, high res hairs, etc...However that means you are stuck with 1k textures in the environment.  You can use amidianborn's or you can use what I use and that's Tamriel Reloaded, then install amidianborns caves and Solstheim.
I have 251 mods, indoors I'm locked at 60fps, outside I range from 45-60, with a few stutters here and there, mainly when I'm traversing a lot of terrain quickly.  It's manageable though.
Really tempted to turn my 780 back into newegg and just run two 770 4GB's in SLI, it's a good deal more expensive, but better performance and 4GB's of VRAM might make it worthwhile.