List Fields attempt to do a so-called high quality rendering of the rich text fields in the document. This process is done by extracting the content of the rich text field with DXL. (Domino XML Language). If the document contain large binary objects such as file attachments, images or OLE attachments, this process will be very slow and potentially hinder other functionality in List Fields.
You receive this message when the combined size of all attachments (files, images, OLE attachments etc) exceed the specified size threshold in List Fields.
You may choose to experiment with the size threshold, since the speed of your computer may impact on how much data DXL can process. In addition, people are different regarding patience, and you may be willing to wait a little longer in order to get high quality rendering ?!? You can manipulate the size threshold here.