Chinese DreamHost customer Robin has written a series of posts about installing the php accelerator and encoder eAccelerator.
eAccelerator is a further development from mmcache PHP Accelerator & Encoder. It increases performance of PHP scripts by caching them in compiled state, so that the overhead of compiling is almost completely eliminated.
First Robin investigates the differences between caching the HTML output and caching the compiled PHP script in his test of WP-Cache vs eAccelerator. He continues to ask should we use Zend Optimizer and eAccelarator together? And finally he shows how to install eAccelerator on DreamHost.