This may be OLD now, but it definitely helped me, and I wanted to post it to try and help anyone else who plays Skyrim on the PC.

Remember that patch Bethesda released a long time ago that supposedly allows your Skyrim to use 4GB or more of RAM? Well, it allows it but doesn't set Skyrim up to do it. In order to make sure that Skyrim is actually using all the RAM available to it, you need to go to your INI file and check for this line under the [Papyrus] section:

iMaxAllocatedMemoryBytes=XXXXXXXX

If you don't see a line like that, then the fix isn't actually being used. If you don't see that line, you can manually type it in, and then replace the Xs with one of the following numbers, depending on how much RAM you have:

If 4GB RAM - 2000000000

If 6GB RAM - 3000000000

If 8GB or MORE of RAM -4000000000

I just found out about this, and it definitely helps. Original info found here:http://www.rcrncommunity.com/five-quick-skyrim-tweaks-you-may-not-know

This is just one change, but I feel its the most useful and the one more people should know about.