Slow query execution over high latency network

Hello,

When executing huge (10kb), hibernate-generated queries I noticed that
when executed remotly over  high-latency network (ping to server
200-400ms), the query takes a lot longer to complete.

When the query is executed remotly (psql or jdbc) it takes 1800ms to
execute, when I issue the query in an ssh terminal, I see the results
almost immediatly.
So although I should see the same latency over ssh , its way faster over ssh.
The transmitted data is small (the wireshard-file has 22kb, attached),
and even though the umts-network is high-latency its relativly high
bandwith (~512kbit/s up, ~2mbit/s down).

Any idea whats causing this? Maybe too small buffers somewhere?
For me it poses problem, because I am working on a 2-Tier java
application which should connect to postgres remotly - however with
every more complex query taking 2s its almost unuseable over wireless
networks (umts).

Thank you in advance, Clemens