Wow....looking at the charts on that page performance is horrible on windows/mssql. 
That is my experience as well from the few windows installs I have worked on. It would definitely be worthwhile moving the site to a linux server.


I found this page which may help.:

https://forums.iis.net/t/1041540.aspx?More+information+on+Error+0x800703e3ums.iis.net/t/1041540.aspx?More+information+on+Error+0x800703e3