Are you using SharePoint workflow to upload the attachment? Or do you have code in your form that is uploading the attachment to the list item?
You might want to take a look at our qRules product which has built in file attachment upload to SharePoint lists from InfoPath:
http://www.qdabra.com/en/products/qRules.aspx
We have not had any reports of timeout issues due to file size, 200kb is not that large so it doesn't seem like this would be a SharePoint timeout issue.
Ted