Hi Josh,
Thank You for your all updates and your sample.
I was able to reproduce the issue that you have mentioned here. This issue has been fixed in our new version 5.1 whose RC was released last week. Could you please open a Direct-Trac incident with regard to this issue, so that we can provide you the link to download the v5.1 version RC. Please open the new incident with the below subject.
Subject: 60145 - WordDocument taking indefinite time to Save
Herewith I have attached the Sample document that was created using your sample with our new version v5.1.
SampleDoc.zipPlease let me know if you have any other queries.
Thank you for your interest in Syncfusion products.
Best Regards,
Bhuvaneswari.