Stabilization and Optimization mods - http://tesivpositive.animolious.com/?page=stabilization_and_optimization_mods <-- get at least OBSE, OSR, Streamline and Optimised Distant Land MAX
If you have on-board sound, get Quiet Feet MAX as well. Don't forget the OMOD Installer.
Oblivion.ini Tweaks - http://tesivpositive.animolious.com/?page=oblivion_ini_tweaks#OnBoardSound <-- The on-board sound tweaks for the Oblivion.ini help tremendously as well
Edit: If you do not use OBMM, it will save you a few headaches.
OBMM - http://tesivpositive.animolious.com/?page=obmm
OMOD Installation - http://tesivpositive.animolious.com/?page=omod_installation
OBSE - http://tesivpositive.animolious.com/?page=obse <-- In case you need further instructions for installing it