If you want better performance, download confident enb performance version (the one without SSAO). I basically have the same stats as your computer (Intel i7 2600K, MSI NGTX 580 Lightning, G-Skill 8GB RAM, Kingston SSDNow V200 128GB) and this fixed it for me. I was using confident ENB before with SSAO and I would get frame rates around 20-40 with the 1.3 patch. I removed SSAO and now I get 45-60 in Whiterun (because I have switched it to a 120HZ monitor, it actually jumps to about 70-120fps in some areas inside buildings and small caves) with the 1.4 patch. Patch it with 1.4 and you'll get a massive frame rate boost. You can still mod with it. I have so many mods on this game right now.