Lucene Merge Factor

1. lucene.indexer.mergerMergeFactor=8

higher the value faster the response as in memory indexing increased
and the communication between disk and RAM is decreased.

2. Increase the number of open files allowed on machine
ulimit -n

Open files = (1+ mergefactor) * Filespersegment

3.http://wiki.alfresco.com/wiki/Index_Merging_Performance