Oracle, MySQL and Sybase don't fork processes for connections.
Oracle forks a process to handle a connection by default, unless you configure it with the MTS option. MySQL starts a new thread for each connection, which under Linux has the same overhead as starting a new process.
Here's what Oracle has to say about bind variables, hard/soft parsing etc.
The following example shows the results of some tests on a simple OLTP application:
Test #Users Supported
No Parsing all statements 270
Soft Parsing all statements 150
Hard Parsing all statements 60
Re-Connecting for each Transaction 30
http://download-west.oracle.com/otndoc/oracle9i/901_doc/server.901/a87504/ch1.htm#25635
