Finally my migration from b2evolution to WordPress is complete and the transition was overly painful, as there was no direct importer available. Many 404’s (which I manually monitor with the WordPress plugin ‘404 Redirect’) caused quite a lot of trouble.
After hardening the installation and tuning Apache, MySQL as well as WordPress, the final step was optimizing the old images.
If you have access to Java on your server, download the Java smush.it application and then run it on your server:
java -jar ~/smushit/smushit.jar -imageDir=[path-to-images] -verbose=true -dryRun=false -imgExtensions=gif,png,jpeg
The above will optimize all images recursively and resulted in a 35% reduction in image size. Install the WP Smush.it plugin afterwards which optimizes newly updated images as well as allows you to bulk-smush existing images.