So I did a little more digging around why the merging is taking so long, and it looks like merging postings is the culprit.
On the 5.4 version, merging 500 docs is taking approximately 100 msec, while on the 6.6 version, it is taking more than 3000 msec. The difference seems to get worse when more docs are being merged. Any ideas why this may be the case? Yasoob -- Sent from: http://lucene.472066.n3.nabble.com/Solr-User-f472068.html