The Tile charts on the Experience view need to be calculated. This message means that there was more data than the default value set for the clamp. The default value is 500. It is a protection put in place for Enterprise Manager.
Users have three options:
1. Drill down into more detailed view. (Less transactions will be calculated)
2. Apply some filters for the top level cards. (Less transactions will be calculated)
3. Raise clamp appropriately:
This can be done using the property introscope.apmserver.atc.landing.clamp.size=500 in the EM properties file. ( not present by default ). In a cluster, this would be set on on the MOM. But be careful when raising this property as you may need to increase the -Xmx startup property and also you should expect slower rendering time for top level pages where there are too many transactions.