Yes, it was a capacity planning issue because they hadn't tested the schema for that load. As soon as they rebuilt the clustered index to remove the fragmentation, things sped up. Not a SQL problem, a design and planning problem.
And the CAT team article didn't say anything about what it *wasn't* - only that it was a capacity planning issue. That's a nice catch-all for all kinds of performance problems...
Paul Randal
CEO, SQLskills.com: Check out SQLskills online training!
Blog:www.SQLskills.com/blogs/paul Twitter: @PaulRandal
SQL MVP, Microsoft RD, Contributing Editor of TechNet Magazine
Author of DBCC CHECKDB/repair (and other Storage Engine) code of SQL Server 2005