Currently each time we call getNext() on a forward index cursor, we'll do an extra check against the key as a workaround for WT-2307. Since that bug has been fixed, this extra comparison is no longer strictly necessary. Removing it from production builds should get us a modest but non-trivial performance improvement, at least for workloads where the index fits in memory. If the index entries need to be read from disk, then the cost of the comparison is rendered trivial.