This is what worked for me back in the day to fix stuttering:
1) Select "Throne Of Bhaal"
2) "Single Player"
3) "Import Game"
4) Load your save
5) Wait for the Autosave to kick in
6) Go back to the main menu
7) Select "Baldur's Gate" (If you are playing from BG1)
8 ) "Single Player"
9) "Load Game"
10) Then load your save you used when you Imported
And also be mindful of your bags:
17. Inventory management(no stacks that have more than about 200 items, in a bag, arrows etc.), -might also help, as in if you drop an item to the ground and or store it in a stash the stuttering might go away in a few seconds there after. And do not carry too many bags of holding and the like storage_items, or give into the your greed and use the moving bag of holding in the donkey mod(W_mule).