tcp vs. udp queries performance difference

[KyoungSoo Park]

Hi,

I'm not sure if this is relevent to this list, but I have a simple 
question.
Is it generally better (in terms of overall latency) to use persistent 
tcp queries to a nameserver (over typical udp queries)
when you have a high volume of names to lookup consistently ? ( I mean 
A-record lookup from a normal client.)
For example, when you're running a proxy server, you get a higher 
pressure of name lookups, so
I think it's better to use a persistent tcp connection to a nameserver 
rather than getting screwed by udp packet losses.

However, I tested this, but I don't see big difference between two methods.
Even worse, the persistent connection's overall latency seems worse than 
the udp queries in many cases.
Is there anyone who's already experienced this and possibly knows why?

Thanks,
KyougnSoo

PS. I sent this to bind9-users too,  Sorry if you see this twice.