Perf differences between timestamp and timestamp with timezone

Hi all -

I'm considering changing all my "timestamp" columns to "timestamp with
timezone" columns instead. The reason is I want to use UTC time for
everything in the DB and on the web server, and only ever convert to local
time on the client itself. I could use a timestamp and just "know" that the
timezone is UTC, but npgsql seems to handle this a lot better (like set the
"Kind" property to UTC, etc) if you have a timestamptz column type.

I'm curious if there's any perf drawbacks to doing this, or would the only
perf hit be if I were comparing timestamp with timestamptz and doing all
sorts of casts and stuff. Thanks!

Mike

PS - If there's any way to make npgsql just manufacture UTC DateTime objects
to begin with, that would be nice too.. Digging through the code I coudn't
find an easy way.