Ranplan is running very slowly and I am seeing a lot of warning messages regarding temporary files, especially when importing CAD files and background images.

Your temporary folder may be getting full and should be cleared, don't worry you won't lose any of your settings or personal information.

To clear your temporary folder please navigate to \\Users\UserName\AppData\Local\Temp and delete all the files and folders in this directory, ensure that Ranplan is closed when you do this.