I thought Morrowind was running slowly so I tried the following:
-Deactivated like 200 esps (but I still have textures/mesh changes)
-Replaced EVERY texture (tga/dds/bmp file) in the Textures directory (or recursively contained therein) with a 64x64 placeholder texture
-Turn off Anti-Aliasing, Distant Land, and Hardware Shaders

This had almost no effect on frame rate. My Core 2 Duo (E3800 I think?) CPU is typically at 60% (i.e. one core is probably fully occupied) and my frame rate is around 20 fps outdoors if I'm lucky.

Is there any way to speed things up apart from a new CPU?
How can an 8 year old game bog down the CPU like this? Could the problem be that my fancy meshes have too many vertices, and there are per-vertex calculations on the CPU?

OK, I think I tracked down my problem

This mod "Animated_Morrowind - Expanded.esp" is dropping my FPS from 37 down to 22 reproducibly in Balmora, i.e. a 18 ms / frame cost. :swear:

Even if this mod were the ONLY esp/esm in existence, and the rest of the Morrowind world were deleted, I wouldn't be able to break 55 fps.

Edit: Turning off MCP 1.9 "extra bones support" didn't help.

Wild guess: there are some superfluous vertices in outer space, or the animation skeletons contain huge translations rather than having each node be centered. The result is giant bounding volumes and lotsa animated characters winding up in the viewing frustum?

it would all really depend on what mods and texture/mesh replacers you are running. i have seen that a bad script will ruin your fps. i have a weak system and dream of the fps you complain about but thats my problem. are you seeing any thing it the "warnings.txt"? are you using mlox to avoid mod conflicts? MGE? there are a lot of things that could be at fault for low fps and Balmora is usually for me the slowest place in MW.

As far as I know the "high detail shadows" ini option can cause massive slowdown when certain NPC meshes come into view. You also haven't stated your graphics card, if it's an Intel then it is probably doing the vertex shaders on the CPU.

Suggestions:
Open your Morrowind ini file and change this line: Max FPS=240 to Max FPS=60
Turn off shadows.
Make sure your Music slider isn't fully muted, which would be all the way to the left. (If you want to disable music, move it one tick to the right of the left side)

For an additional fps boost, you could install the http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=2644.
Removing some rocks to get a nice frame rate is a good deal if you ask me. Do note that the admin comments are wrongly stating the presence of the 72 gmst. I downloaded a fresh copy of the mod and checked with tesame, no gmst were found.