Unfortunately, I cannot forward the form as it contains client data.
I have tested signing another PDF I've created with 2 fields using the same the digital ID's, and the process completed quickly.
Perhaps the problem lies with the size of my form which has 20 pages with 50 fields (on average) per page.
When signing the document, the signature details appear, the "saving file" temporary status bar appears and THEN the hourglass kicks in and takes 5 minutes before control is returned. Is there validation particular to the signing process I can disable? Alternatively, can I specify which pages are certified instead of the entire document?