Hello everyone!

Just reinstalled good old Oblivion after seeing the lates Skyrim-Trailer.
Sadly I ran into extreme performancedrops right after beginning the game.
System-Specs:

-AMD Phenom II 940BE CPU @ 3,4Ghz Watercooled
-Asus HD5870 1GB @ Stockcore Watercooled
-6GB DDR2-800 RAM
-Creative X-Fi Titanium PCIe
-OCZ Vertex SSD/Samsung F4 HDD
-Vista 64bit
-Windows, DirectX and Drivers complete up2date
-Oblivion is installed @ Samsung HDD - HDD was defragged after installation, Oblivion is still "vanilla" (except for some .ini-tweaks) with latest official patch
-Resolution is 1920x1080, 4 adapptive multisampling AA/16x AF/Vsync on via Ati Tray Tools

Now my Problem: Performance is perfect (=60fps) until I see some NPCs with NPC-Shadows enabled (happens in interieur and exterieur).
As an example - when playing the tutorial and the dark brotherhood NPCs appear + friendly NPCs in view my framerate drops down to 30fps
Another example - after leaving the sewers and fasttravelling to the entrance of the imperial city my fps are, again, @ 60fps. After walking over
to the paddock and watching at the 2 NPC + horses their my fps drop to around 30fps. After disabeling NPC-shadow (other shadows don't matter)
my fps are up to 60fps again.
I monitored the CPU/GPU-Ussage via Everest on my G15-LCD and CPU-Ussage is somewhere around 30/10/5/5% - GPU is around 50%
It doesn't matter if I enable/disable AA/AF/Vsync - except the performance rises even more whith NPC-Shadows disabled and GPU-Usage gets even
lower.
Also is there no performance-difference after changing the shadowquality via .ini.

Oblivion doesn't recognize the HD5870 and sets the graphicdetails to "low".
I've set up windows to max. performance - CPU stays @ 3.4ghz all time.
I also allowed 3.0 shaders in the .ini and tried to exchange the used shaderpack (no 17) with shaderpack 19 to force the usage of shader 3.0.

Anybody got any ideas why this happens? My Machine should handle "vanilla" oblivion without any problems. Also I didn't have these problems with
my old PC (C2D E6300 @ 3Ghz, GTX260, 4GB Ram) and could run Oblivion completely maxed out with OBSE/OBGE and a lot of Texturereplacers...

Greetings from germany
Frank

Have you used the 4Gb patch so the vanilla game can take advantage of the extra RAM yet?

Nope - Oblivion is/was completely stock.
But the Ram-Usage shouldn't be a problem when using Oblivion without any mods.

Since it looks like my OCZ Vertex SSD died just some hours ago, I need to reinstall
Oblivion etc. first, before I can continue with my testings. But as far as I can remember
the RAM-Usage was around 30% - so no problems there.

Greetings
Frank

Shadows are just one of the (many) things this game doesn't do very well. They've always had a performance hit coupled with turning them on. NPCs are resource hungry in the first place, too, so setting the shadows up to max in this game (or even just turning them on) can slow down even the highest end systems. It's the same way for water reflections, sometimes people just get hit stupendously hard when they are turned on. One of the many limitations of Gamebryo for yah... :shrug:

You might have to just turn the shadows off and live without them. Don't worry, you won't lose much, actors are the only things in this game that can cast shadows, anyways.

Oblivion doesn't recognize the HD5870 because the card was made after the game was released, so it's not in the database. You should be fine running this game on Ultra-high unmodified, though you might want to turn things down if you are going to toss in mods like Better Cities or RAEVWD.

Also, forcing shader pack 19 has been proven to be worthless, it does nothing for the game's performance or graphics quality. Just stick with the shader pack the game chooses based on your hardware, there's no point in changing them.