Slow DNS Query

[Kevin]

Hello,
I'm running bind 9 on RH9.0, the websites and DNS are on the same server, I
always feel DNS is too slow, take up to 5 ~ 10 seconds, but dnsstuff.com
rated the DNS "A", I'm really confused.
Someone suggested me use forwarders, I don't think it can improve the speed,
since using forwarder will add one more step to the DNS resolving process,
and dnsstuff rating got lower when I tried forwarder. Someone told me it's
probably my ISP's problem, but other websites I visited are pretty fast.
This problem has bothered me for serveral months, any suggestions are much
appreciated!
Regards, Kevein

P.S. posted two days ago, but didn't see my post.