Nevertheless, the point is this: If you have a PerformancePoint (PPS) filter linked to an attribute in a dimension, and the keys change, your filter will break. 

Lets say you have a PPS dashboard containing a filter and a scorecard.  The filter is linked to the Category attribute in the Product dimension.  If the keys in the Product dimension change from Bikes having a key of 3 and Accessories having a key of 4 to Bikes having a key of 4 and Accessories having a key of 5, then whenever you select Bikes in the filter the scorecard will display the results for Accessories.  If these were the only two members in your dimension I’m not sure what would happen if you selected Accessories but I assume the scorecard would just show empty cells.  Or spontaneously combust.

To fix this all you have to do is edit the filter by clicking on Member Selection, going through the wizard, and publish/deploy your dashboard.

http://performancepointblog.com/2009/03/performancepoint-fix-slow-rendering-dashboard-issues-with-internet-explorer-8/

When implementing a PPS dashboard, the browser of choice should be Internet Explorer 8.

Whereas IE7 only supports up to 2 concurrent connections to the server, IE8 supports up to 6 concurrent connections to the server.  In cases where there are a lot of objects on the dashboard you should see a significant increase in performance.  This is because each object on the dashboard (each filter, each scorecard, each chart) requires a connection to the server.  Instead of rendering only 1 or 2 objects at a time, IE8 can render up to 6 at a time.