Attaching documents in QuickBooks desktop shouldn’t affect the performance of the software. They are saved on the computer hard drive in a separate folder, and they are not included in a back up of the QuickBooks company file either so that backup file does not grow either. All attaching does in QuickBooks, is to enter a pointer to the hard drive location for the attachment folder.
If you experience slowness with QuickBooks, there may be other reasons like due to a large company file or network issues.
Script error when using payments account applications and/or websites
From the article:Script errors occur when there is a problem executing a command that involves our application(s) on your computer attempting to access a web-based (internet) feature. This may also involve third party applications (e.g. Java, Flash, ActiveX, etc.) interacting with our online applications (e.g. online service center, QuickBooks Online, etc.) and/or our desktop software (e.g. QuickBooks Pro, Premier, Enterprise, Point-of-Sale, etc.) …