SQL Server system views VERY slow at one computer
This sounds more like a name resolution / reverse lookup issue. Have you tried adding an entry in the hosts file on the "Computer outside of domain"?

Windows keeps it in C:\Windows\System32\drivers\etc

Edit - https://stackoverflow.com/questions/10872557/how-slow-are-tcp-sockets-compared-to-named-pipes-on-windows-for-localhost-ipc