Using Trace to Monitor and Audit Analysis Services - Microsoft SQL Server 2008 Analysis Services - page 781

We didn't change much in the query, but this time there's quite a difference in the results
presented in SQL Server Profiler (see Figure 38.15).

FIGURE 38.15 SQL Server Profiler shows the results of your query.

Even though the events are pretty much the same, this query produced an extra request
for cell results—that is, data. The server makes an extra trip to retrieve data before it can
populate the axes.