Well, I got the game but not even the main menu runs smoothly (Unless 20 FPS is smooth) and sometimes during gameplay the game slows down (From 60 FPS to 40-30).

This are my specs:

Gigabyte GTX 460 1GB OC
AMD Phenom II X3 720 @3GHZ
4GB DDR3 Kingston Value RAM
1TB Hitachi HDD

I have the exact same problem (and graphics card by the looks of things). It makes the game damn near unplayable at times. Especially during combat. I hope someone has a solution to this problem.

At first I had several issues when running this game, but I managed to fix most of them by following tips I found here in the GOG forums. Right now the game runs quite well and the biggest issue I have is the slowdowns when I view the stats page (The one that shows the player stats and the items that are equipped). Here is a summary of what I have done. Note that I didn't play around too much with these, so it may be possible to turn some of this stuff back on and still get good performance. Once things were working well enough, I stopped trying to improve it.

My system:
Windows 7 64bit
Intel Q6600 (Core 2 quad)
8 GB DDR2 RAM
Geforce GTX 460 (Gigabyte GV-N4600C-768I)
Asus Xonar DX Sound card

Main problems I was having:
- Fast Walking
- Very low framerate and image blackouts in the city of Arx
- Very low framerate in the game menus (Spell page, equip page...)
- Double clicking a corpse or chest would open my inventory but not open the inventory of the target

To fix the issues (or improve them) I set the following settings:
SYSTEM SETTINGS
In the application icon compatibility settings tab
- Set compatibility to: Windows XP SP2
In the NVidia Control Panel / Manage 3D settings
- Anistropic Filtering: OFF
- Antialiasing Mode: OFF
- Texture Filtering - Anistropic sample optimization: OFF
- Texture Filtering - Negative LOD bias: Clamp
- Texture Filtering - Trilinear optimization: OFF
- Threaded optimization: OFF
- Texture Filtering - Anistropic filter optimization: OFF
In the Xonar DX Audio Center
- Make sure the GX button on the bottom right is not lit

GAME SETTINGS:
- Resolution: 1920 X 1200
- Color: 32 bits
- Textures: Low
- Level of detail: Low
- Bump Mapping: Off
- Antialiasing: Off

I find the game still looks good after these changes. The Xonar sound card is great for sound quality, but this isn't the first time that a game behaves incorrectly because of it.

Hope this helps.

I just wanted to chime in that I too have a GTX 460 and am experiencing problems with this game.

Slow framerates in menus and whenever there is text on screen, and also the screen either goes black or gray if you look up for some odd reason.

I really don't want to lower the graphics settings like the above user suggested but I suppose I have no choice. I will try it and report back.

Yeah I know how you feel. But it's really not that bad.

Download the new patch, which fixes performance issues for Nvidia users. Check 'enable rendering fix' if still experiencing issues.

I'm getting even worse performance with a GTX285 on Windows7. 10-15 fps or less in the very first cell for example. The rendering fix option doesn't appear to change anything at all for me. The game's practically unplayable as it is.

I'm sorry if you still experience issues with our game but this patch won't do any miracle and suddenly fix all issues with this 8 years old title. Arx is and will remain a DirectX 7 game in which all menus & UIs use Win95 / Win98 GDI, which is very poorly supported under Vista & 7. Character creation page remains especially slow & laggy, even if disabling antialiasing in drivers control panel may improve perf on a few systems.

However, once in-game, the late 1.21 patch brings some changes to the render engine, and playing around with settings such as "Bump mapping" and "Enable rendering fix" may greatly improve performance. Also, it may be worth trying to enable / disable Vsync in your vid card control panel. Finally, Creative sound card owners should consider creating a custom profile for Arx in Alchemy... ;)

It seems like this game performs much better on ATI cards than Nvidia ones. On my ATI-based system I can force antialiasing and anistrophic filtering up to the maximum and the frame rate never drops below about 35 (at least according to Fraps). Either way I am loving this patch, and the source release is sure to lead to even greater improvements.

This patch and source release coming out of nowhere after all this time does make me wonder what the motive is, however. I'm hoping the motive is Arx Fatalis II. ;)

I'm still having performance issues with those 2 options toggled/disabled. This is the first game I can't finish due to it's technical issues which is a shame since the gameplay is really interesting.

Just wanted to chime in here, even though it's an old thread. None of the suggestions on the GOG forums were working for me until I read about Arx Libertas on the Steam forums. It's a free, open source remake of the engine (still needs the data files from the GOG/Steam install) and it worked like a charm:

http://arx-libertatis.org/

Jeah! This really works!
Thanks for this hint. :)