We have a new patch for Skyrim from the wonderful modders on the PC, and it’s quite good according to the reports. It boosts performance by over 40% and is quite effective.
This patch will improve your frame rate by up to 40% in all CPU-dependent situations, i.e. especially in cities.
It works mostly by rewriting some x87 FPU code and inlining a whole ton of useless getter functions along the critical paths because the developers at Bethesda, for some reason, compiled the game without using any of the optimization flags for release builds.
Thread with download link: http://forums.bethsoft.com/topic/1321575-rel-tesv-acceleration-layer/
Direct link (may change): http://skse.silverlock.org/beta/TESVAL-18.104.22.168-2011-12-22-skseplugin.7z
SKSE Thread with download link: http://forums.bethsoft.com/topic/1321294-wipz-skyrim-script-extender-skse/
To use SKSE, just download it and place it in your main Skyrim folder, then run Skyrim using “skse_loader” which is included with SKSE. The plugin goes in Skyrim\Data\SKSE\plugins (a folder which won’t exist if you’ve never used SKSE, so you’ll have to make it).