– Disable the background music altogether and use only sound effects. The constant loading of new MP3 files for the background music can have a serious effect on you performance depending on your system.
Edit oblivion.ini file and set : bMusicEnabled=0
– Remove the Natural Vegetation part of Natural Environments, especially if used in conjunction with Unique Landscapes Mods.
– Check out this Bethesda forum thread for performance enhancements mods