Which video settings are you using? BF2/fh2 with 64 players can be a real system hog.
Turn Antialiasing (AA) off, set lighting to medium, disable dynamic light, turn off dynamic shadows and/or set texture filtering to medium. The game won't look as good as it did before, but you framerate will increase for sure. Making the game alot more fun to play.
Do some experimenting to find that sweet spot balance between visual quality and FPS
If lowering your video settings isn't enough, try lowering your sound settings. I was told by a couple of betatesters that their framerate increased after turning down the ingame sound setting from 'hardware' to 'software' without any noticeable side effects .
More info about tweaking bf2's video settings can be read here:
http://www.tweakguides.com/BF2_5.html