Any experiences in using loadbalancer for DNS ?

[Udo Zumdick]

Hello,

we have a few nameserver running BIND 9.2.6 as a caching only NS behind 2 Alteon 2208 
loadbalancer in a active standby configuration.
Now, when querying a domain that is not in the resolver cache, the respond for such
a query takes more than 4 seconds, which is much too long. It seems that this is
limited to UDP queries because the same query (dig [...] NS) with a +trace option takes
mostly not more than a hundred milliseconds or so.
Could it be possible that the loadbalancer is the reason for this delay ? Although I
can't take it out of this setting. 

Has anyone an idea for a reason or has similar experiences ?

Thanks in advance,

-Udo