With those numbers, we are at a loss as to why this might be happening. Let us know if you are able to provide a method of reproducing the issue, as other users are not experiencing the issue. We too have sites using the plugin heavily, and have not once experienced the described issue.
Things to look for;
. Out of date plugins
. Is issue happening at a certain time of the day
. Any other server errors (even if they seem non-related)
. Is there any custom code running when the form’s submit is clicked
We await your reply as we remain at your service.