There are a couple of things that have come up regarding performance issues with Word Templates.
1. You can see issues with performance if you have a logo on your template and the logo is too large. The logo needs to be within a certain size. If the logo is too large it can cause the printing of the reports to be slower. If you are adding a logo to a word template report, the logo should be no larger than 32KB. If the file is larger than that, you would need to make the file smaller or be aware you may experience slowness when printing your documents.
This is also true if you are emailing your documents, you may also see a performance issue there when you have a logo that is too large.
2. You may experience performance issues if you are printing a large batch of documents. For example, if you have 500 documents in your batch and estimate 3 seconds to print each document and 3 seconds to email, this could take about 50 minutes. Even if each took about 1 second, it would still take about 17 minutes for that batch.
It is important to note that using the word templates will take a bit longer than using Report Writer as there are additional processes that run. When you use word templates, Microsoft Dynamics GP will first create them each as a separate document and save them in the temp directory. They are then combined into one Word Document to print to the screen. The e-mails and .pdf's are also generated off of those individual documents from the temp directory.
If you are converting the Word Template to a .pdf that you are emailing this would take additional time as it would first go through Report Writer, create the xml, generate the Word document, generate the .pdf, and then generate the email.