frame rate decreasing in netherstorm

I have been five boxing for 6 months now and up until recently have really enjoyed it. I am almost lvl 70 on all 5 toons and currently I am questing in netherstorm. I have noticed a big hit in my frame rates since I started questing there. I went from almost 50 fps down to high 20's low 30's. Is this normal or is something not right with my system? Below are system stats.

Key clone maximizer running on two 22 inch monitors. Monitor 1 runs my main toon at 1680 x 1050. everything is turned low on that accept distance which is 2 clicks from the right and spell effects. monitor 2 runs the other 4 toons at 800 x600 with maxfpsbk at 15 and everything set to low.

vista 64 bit
q6600 2.4 ghz quad core processor
6 gb corsair pc6400 ddr2.
geforce 9800 GTX+
western digital sata drive with all wow data dir's symlinked to the original.

I also have cpu core affinity setup using core 1 and 2 for my main and the other two for the alts. All wow's are running off of one hard drive. any help would greatly be appreciated as I have read some posts with people 5 boxing and getting much higher frame rates.

NOTE: I have already tried turning off questhelper and didnt notice that much of an increase. I also have played around with my page file and set it at 512 fixed which gave me a minor increase in performace.

I think you will find that is probably the last patch that has killed the framerates.
I have just had two weeks off, and was averaging high 50's to 60 (capped at 60) on each instance of WOW.
After I had applied the latest patch on Sunday my average was 30-50.

i reduced my spell effects and i had shadows already on low. I also tried playing with the cpu affinity. no affect. i can't believe the gforce 9800 gtx+ cant handle 5 wows on low settings :)

any other ideas?

I have found the problem to be addons. if i disable them all i get 60 fps no problem. this makes my ui unsuable though in my honest opinion. Is anyone else finding out these have this problem as well?

I had to ditch Questhelper for Carbonite as I and a few people I know had major fps issues after the wrath patch because of that addon. If you use QH, try just disabling that and see what happens.