You can rebuild an index for maximum retrieval speed and minimum disk space using the Optimize feature of Perceptive Enterprise Search. This function is useful if your index is about to be published or is in a static state, but is not normally recommended for dynamic indexes. Note that an Optimize usually takes a little longer than a normal Reindex.
An Optimize requires an additional amount of free disk space to use for work areas during the process. In practice, this is as much free disk space as the ISYS.IXA, .IXB and .IXC files currently occupy.
To optimize an index: