I am not sure what is needed to get the game to run smooth. But here is what I have learned by fooling around. Mind you it is the ripped warez version. The official release might be different, as we all will know in a few days.
So consider this perliminary at best.
I am @ best sound, res 800x600 @ 21 fps, high geometry on the cars, low on trackside objects, medium for pit crew, 16-bit medium textures, trackside objects in front view, no objects in mirrors (still nice track and all the cars), low shadow detail, and all the goodies disabled apart from helmet, tv overlays and mirrors. That is no light map, no heat haze, no reflections (there still is a shine, you just can't see your mom in the grandstands), no bump mapping and all that stuff.
My objective is to be able to run all circuits in any set of conditions and grid positions and never go above PO 100 for more than a split second.
My specs are
AMD Thunderbird 1000 MHZ/100 Mhz bus
Asus A7V 200 Mhz FSB
384 Megs of 133 Sd-ram
Asus v7700 Gerforce 2 GTS 32 megs DDR-ram
SB-Live 1024 player (a type of value card)
1 samsung 3,4gb ata 33 U/dma HD, 1 IBM 20gb ATA 66 U/dma HD 7200rpm.
1 x24 speed CD drive
1 x8 speed CDR
MS non FF wheel USB
As I said I am not sure, as to what makes the game slower or faster. I have set the relay recorder to 90 minutes, and it is all stored in my memory. I have NEVER seen any HD activity in-game, so as long as you have a good amount of RAM, you can have a HD from the stone age with no performance hit. Needless to say, if I set the replay function to 18 seconds, I see no performance difference at all.
What really takes up PO is how many objects you have in the front view and in the mirrors. Reducing those makes a huge difference, and I have even elected not to have all objects displayed in the front view. Selection of textures seem to have little or no effect, that is besides selecting high textures. For some reason I get a PO of 600 with high textures regardless of anything else. This leads me to believe that either the high qual textures have been ripped, not likely since a crash should ensue, OR that 32 megs of video ram simlpy isn't enough. Setting textures to low gives little to no gain, so my conlusion is:
16 megs: low textures/16 medium
32 megs: 16 medium/medium
64+ megs: High
As to the geometrical details, the effect of changing the is slight, which leads me to believe that ALL geometry is calculated by the hardware in the video card. Mine CAN take everything at high, but each increase changes PO by about 4. With 12 settings that is about a 48 PO difference, with the PO rising steeply the more that is turned on, and small PO the more that is turned of. I have GF GTS 2. I think that you need GF3 or above to go to everything high. Nevertheless, I cannot use heat haze (looks SO COOL), lightmaps, bump mapping and reflections and so on. I am pretty sure that ALL of this is taken care of by the Hardware on the video card. So Geometry and Goodies are handled by the video exclusively, and must be balanced with each other. GF 4 should be able to carry everything at max.
I have seen (@ alpha) systems with the same specs as I have with a Voodoo 3, instead of the GFS GTS 2. Result 640x480 @ 10-15 FPS. GFX cards mean a lot!
Changing sound settings from 3D hardware with eax to 3D hardware without eax, or 2d hardware, gives no PO change WHATSOEVER! Again everuthing is handled by hardware on your soundcard.
What really makes a difference is the FPS and the resolution. I cannot go to 1024x768, except if I cut every detail. Every increase of FPS gives major PO increases. FPS @ 21 is very good. Frankly, I cannot really tell when it is set to 21 or 40 apart from the PO load, so don't be scared of going low. On the other hand below 20 seems choppy to me, but it frees up huge amounts of PO. Also strains on PO for me go close to 100 when there are loads of cars and action and it goes as low as 40 when there are no cars, and little to no objects on the trackside.
It would seem to me, that the major strain on PO can be broken down thusly for my machine: About 40 for cockpit, track and objects + the physics and sound. The better textures the high the load on my vid ram, and if I go to high, the vid ram constantly swaps and hence the AGP bus is overloaded and everything is choppy. The more cars and objects the higher PO, which can be referred to two things. The GFX card needs the geometry detail and it needs the textures. Since there is no HD activity at any point, everything comes from system RAM and I have enough to hold every piece of info the game wants in my 384 megs. The crucial issue is then: HOW fast is your RAM, and HOW fast is the PCI, AGP and CPU bus frquency. If the game is calling more than the bus can transmit, the PO rises steeply and will quickly go above 100.
So if you are looking for good performance, these are the crucial bits:
1) enough and fast system RAM to hold and transmit game info. 384 is definately enough, and I expect little to no gain by higher amounts. The game would like faster ram than sd-133, but it can do.
2) A mainboard and CPU with a high bus frequency. It seems not so important what the internal frequency of the CPU is, it is the ability to retrieve and send info that counts, hence the BUS - external - frequency (divide speed with multiplier) is the important thing. Mine is at 100x10 - 1000 which I am seriously considering changing to 133x7,5 - 1000. I just need a electrocurrent pen to short my CPU multiplier lock
3) Hardware accelerated GFX card the supports TnL. Geforce or better. See above list for and text for ram and chipset specification estimates.
4) Hardware accelerated soundcard. Can be compensated with a fast system.
5) The correct configuration and the best drivers for your hardware.
So whats your experiences with GP4 and performance?
It's only after we've lost everything, that we are free to do anything.