Hello I'm Obviously Shadowscales formerly Evil2828 (I thought I might try a more unique name..)
So anyway, as the title says
How would I go about Lowering the poly count on nifs without using pyffi and without making the nif take 3x the amount of kbs?
I run Oblivion on a Toshiba nb100 netbook
(before you tell me to buy a gaming laptop you need to realise I used to have a laptop from 2001 with only 1.0ghz PIII and 8mb graphics and that was intergrated....)

So my netbook only lags on high poly models or models that were "optimised" with pyffi
I want to lower the poly count on most meshes in the game without ruining the mesh (pyffi) or increasing the file size by 3x
how would I do this?

A larger size mesh is not always a bad thing. Optimization does not always mean the size is reduced either. I'm not sure what you mean by stating that PyFFI ruined your meshes. I've had very few issues with PyFFi that were the direct fault of PyFFi.

PyFFi'ng your meshes is by far the best way to increase performace. Running my Oblivion - Meshes.bsa through PyFFi made the most noticeable performance gain out of all the "tricks" or "tweaks" I've tried, hands down. Without upgrading hardware I don't think there are many other options out there.

You probably don't want to hear this ( in fact, you said as much ) but you're using the wrong computer for this game, period. The netbook you have is incapable of giving you what you want.

Intel Atom N270 1.6Ghz CPU, 1GB RAM, Intel Graphics Media Accelerator 950, 5400rpm harddrive. I think you get the picture.

You really should consider either getting a gaming laptop or simply investing in a good desktop PC. Not just for this game either. If you intend to do any sort of 3D gaming you'll need something beefier than your netbook.

I tried pyffi a while ago, all it caused was trouble........
or maybe those were the "fixed" uop meshes.......

I ran all of my meshes, including those in the Oblivion-Meshes and Shivering Isles-Meshes BSA files, through PyFFI and am glad I did. Huge performance gain and they don't look any different than before.
The only way PyFFI can mess up your meshes is if you either (1) use an early version of it, or (2) try to optimize meshes such as Helmets or Hoods that are morphable (i.e. are different sizes depending on who's wearing them).

Basically, you should not PyFFI any helmets, hoods, hair, or teeth. Everything else should be fine.

*sigh* my pc works fin on oblivion using oldblivion with all lighting passes and bump maps with refraction shader.....
It's just certain meshes....

I want to know how to lessen the detail of the meshes, not remove invisible polys and vertices

As far as I know, the only solution that meets your conditions is for you to edit the meshes yourself, or make new ones. Pyffi is the only automated tool for optimizing meshes; but since you have been unable to use it successfully, and you don't have the option of using better hardware, it seems now may be the opportune time for you to take up 3d modeling. I am sure there are others who would be appreciative of your work.

In short, there's no easy way to do what you want. You'll have to take each mesh into a program like 3DStudio Max or Blender and remove things manually. You're looking at hours and hours of work.