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.