Many users encounter rendering speed changes when upgrading from older versions (specifically Vectorworks 2010 and older, which used the Lightworks rendering engine) of Vectorworks prior to the introduction of the CineRender / Cinema4D Rendering Engine from MAXON. The following is a list of the main causes of these slowdowns: 1) The file was created in a previous version of Vectorworks - Go to Tools > Purge, perform a full purge of the document to remove extraneous data. - Go to Tool