View indexing performance on Domino 8.5 - twice as good as 7

A colleague of mine did a test this week. How does View Indexing perform on Domino 8.5 compared to version 7?
And the results are looking real good. Generally the View indexer on Domino 8.5 indexes the same number of documents in half the time compared to Domino 7.
A quick look at the test environment:
He created a test environment on Windows 2008 server.
He had four databases. Each database contained four views.
Database 1: Contains four views with columns that sort text.
Database 2: Contains four views with columns that display un-sorted text.
Database 3: Contains four views with columns that display sorted numbers.
Database 4: Contains four views with columns that display un-sorted numbers.
Database 5: Contains four views with columns that display categorized text.
Database 6: Contains four views with columns that display cascade-categorized text.

Each of the four views in each database contains an increasing number of columns. The first view has one column, the second view has two columns and so on.
For instance Database contains:
One view with one catageorized column.
One view with two catageorized columns.
One view with three catageorized columns.
One view with four catageorized columns.

What he then did was to start out with empty databases.
For each database he now created 100.000 documents.
This is done by a LotusScript agent.
The agent sets view.autorefresh=false on all four views.
It creates sets of 1.000 documents and then does a view.refresh. It takes note of how much time was used for indexing each view.

For this test size the general findings were these - based on averages:

• Performance is increased in all types of indexing (the 6 database types - categorized, unsorted etc.).
• The top performance increase is with views with fewer rather than more columns. So a view with one sorted column has a performance increase that is larger than the performance increase seen on a view with two sorted columns. For instance a view with one sorted column indexes four times faster on 8.5 than on 7. A view with two sorted colum indexes two times faster on 8.5 than on 7.
• For unsorted views there is practically no performance gains.
• Generally speaking indexing is around two times faster with Domino 8.5 than seen on 7.

Some of us have experiencing problems with the View indexer on Domino, so bringing down indexing times by halt of course is great news.

My good colleague Morten is preparing a new series of tests where he is indexing 1.000.000 documents.