@OP, considering that your CPU is around 4 GHz, you should be fine with ave. FPS in BH&H2. Generally speaking, BH&H2 throws less aircraft up in the air than the UE/PE vers. of WoFF - so feel free to run BH&H2 at "medium" congestion/air activity settings for most of the war - and your FPS should for the most part stay around the 60-70 FPS range. No need to fly with light or very light flight activity settings, as was sometimes recommended for UE/PE WoFF.**
** NOTE: loading any of the various water mods. (in unmodified format) by Xjouve will drop FPS on ave. by about a value of 10-15. If interested in running the water mods. - see my casual campaigns thread (can't remember the specific page no. of that thread now) - there is a post there (somewhere around the middle of that long thread) which gives directions for how to create a "lite version" of the 1.1 total water mod. by Xjouve, to help with FPS.
Cheers all and happy flying,
Von S