Hi Tailspin,
I tried reducing the bitmaps to 512, but it didn't work for me. Having said that it could work for others. Someone has stated that the polygon count for FE models tends to be higher than for models is SFP1, so maybe it's that that can cause some to experience frame rate issues. The frame rate hit does seem to be linked to the fine details (rigging etc).
I've read that reducing the in-game horizon setting to NEAR can help.
Whatever, it's still a great model and won't stop me from flying it