[OT] MySQL is bad, but THIS bad?

Sorry to interrupt, but I have had the "opportinuty" to have to work with
MySQL. This nice little gem is packed away in the reference for
mysql_use_result().

"On the other hand, you shouldn't use mysql_use_result() if you are doing
a lot of processing for each row on the client side, or if the output is
sent to a screen on which the user may type a ^S (stop scroll). This ties
up the server and prevent other threads from updating any tables from
which the data is being fetched."

How do busy web sites work like this?

What is the best way to go about creating a "plug and play," PostgreSQL
replacement for MySQL? I think the biggest problem getting PostgreSQL
accepted is that so much code is available for MySQL.