A sandboxed solution is a new concept in Microsoft SharePoint Foundation that allows site collection users to upload their own custom code solutions. A sandboxed solution uses a subset of the Microsoft.SharePoint namespace. These objects are marked in the object model to show their availability in a sandboxed solution. All sandboxed solutions are stored in a solution gallery. In addition, there are facilities provided to help server farm administrators monitor and validate solutions that have been uploaded to these galleries. Performance can be monitored by measuring CPU execution time, memory consumption, and database query time. You can also monitor other aspects of operation including abnormal termination, critical exceptions, unhandled exceptions, and data marshaling size.