Chris Webb doesn’t want to wait:
There are four columns: Date, Town and two measures. One measure called [Fast Measure] is, as the name suggests, very quick to execute; the other measure, called [Slow Measure], is very complex and slow. The definitions are irrelevant here. Notice that there is a filter on this table visual so only the rows where [Fast Measure] is greater than 1 are shown.
If I measure the amount of time to render this table in Performance Analyzer, it takes around 17.5 seconds to run. However, if I remove the filter on [Fast Measure], the table only takes 8 seconds to run. Why? The filter is on the fast measure and surely more rows are returned without the filter, so wouldn’t the slow measure be evaluated more?
Click through for the answer.