Parameter binding is a database optimization, it generally allows the
usage of statement caching and avoid the database having to re-parse every
SQL statement. The performance loss or gains probably has little to do
with EclipseLink, but with your database. Normally you use parameter
binding in combination with statement caching to avoid the cost of
creating statements entirely, you can also enable statement caching in
EclipseLink if using EclipseLink connection pooling, otherwise you must
enable statement caching in your server's DataSource configuration.