10.3 Server – Extremely slow indexing when using .sitx files

The problem is easy to explain and easy to replicate, however, I have no idea why it does this or how to get around it. Basically, we store archived files from an all Mac production environment in a folder that is indexed manually as it is updated on an OS X Server 10.3.x. The indexed folder (job archive) is then searcheable web share via the server Sherlock web plug-in. We have used all types of files in this folder when indexing without issue, although it largely consists of .sit files of complete jobs folders. Indexing of over 90,000 files usually took minutes, however, if you place a group of .sitx files in the folder to be indexed, the indexing process becomes extremely slow, taking as long as 8 hours to complete. Remove the .sitx files, and it is back to indexing in minutes. Is there any work around that can make indexing faster with .sitx files? Has this been resolved in Server 10.4.x? Any help would be great. Thanks.