I've found various resources such as this one stating that in previous versions of Internet Explorer, IE can be configured to use a process per tab upto a certain number of processes by using the registry key:
HKCU\Software\Microsoft\Internet Explorer\Main – TabProcGrowth (string or dword)
I have tried setting this to both string and dword types with decimal values such as 5 or 20 on Windows 10 64bit with IE 11 (11.589.10586.0) to no apparent affect whilst observing in Windows Task Manager. I expect separate Internet Explorer processes to show per tab in the same way as when I open the developer tools a new process appears.
How is this controlled in IE11?