Hi all,
I dont know if my case is exact to what you might be experiencing but, it might be worth a shot.
I run an XP (SP2) machine, 2.6ghz processor 1gb or ram and a ATI 9250 card. Seemingly tied to the last update, my FR's went into the toliet to the point the game was becoming unplayable.
It was not my ISP as my wifes Vista Machine (she plays) allways maintains a good 60fps, on high res with no issues. I have been pulling my hair out. Turning all the resolution down to where it looks like pong, running everything as clean as posibile via FS autostart etc.
But still, FR's go to 1-7fps whenever many other contacts are around or fire/smoke etc.
Before I went out to get a new PC, I took a shot at a new Graphics Card except, this time I got an AGP slot card instead of the PCI bus I had before.
Voila! everything is now smoking fast with no issues at all. Oddly to my availibile amount of RAM also increased to the full 1024 from 956 it was showing (still dont know why).
Now I am up to full resolutions maintaining 50fps with no issues at 512mb. I have been increasing and am going to go with 1024 next to see how it works.
This might not be your case but, for me changing the card to one ofr the AGP bus instead of the PCI bus cleared everything up