DISCLAIMER: Performance for ENB presets will differ from user to user depending on your system specs. I have an under-powered computer and ENB presets give me a far greater framerate hit than they will other users. Here are my specs:

Core2Duo E8500 @3.16ghz
4gb 1600mhz RAM
1GB ATI HD 6850

After posting my other comparison: http://www.nexusmods.com/skyrim/mods/54971/?

People wanted to know the framerate impact of each preset. This should help :)

With my mediocre computer, I have a difficult time running any but the most optimized of ENB presets. If you're like me and want the benefits of ENB, but need help choosing one that doesn't kill your framerate, perhaps this will help.

I took my favorite presets and some performance presets and with those, I snapped 900+ screenshots, using FRAPS, with the framerate showing in each screenshot, so you can see the exact impact it has on my setup.

24 ENB presets
900+ Screenshots

skyrimprefs.ini set to High
2x AA
16x AF

Presets used:
Aeon Fantasy ENB
BLEAK ENB 119
Evok ENB 119
Gameplay Performance ENB
joeytrackRC1
K ENB 168
K ENB Pure Light
Kinematic ENB 168
Kinematic ENB Southern Lights
Kountervibe ENB Reborn 168
Kountervibe ENB Northern Lights
Minimal ENB
Natural Lighting and Atmospheric ENB
Poupouri Cinematic ENB First Seed 168
Project ENB Climates of Tamriel 119_Realistic Preset
RealVision ENB Option B
Saraan Suum ENB
Seasons of Skyrim ENB HD6 Tribute Version 119
Snapdragon ENB
Somber 3 ENB_Beren's Edit
Tundra ENB_Vibrant Edition
UNBLEAK ENB 119
Z ENB
Zoners High Performance ENB

I hope this helps. Enjoy!

If you want a more in depth image comparison, minus the performance, check out my other "mod":
http://www.nexusmods.com/skyrim/mods/54971/?

It contains a full 90+ ENB presets, but I didn't have the fps counter enabled for those shots.

Cheers!