So yesterday I got an idea to check how much CoH2 uses my GPU, CPU etc..
So the thing I noticed is that CoH2 uses around 30% of my GPU and around 40% of my CPU
I have been plagued with slowdowns/lag recently so I have been looking into this.
My problem turned out to be temperature issues; I installed another fan and am now running quite happily on an old AMD FX-8150 Eight-Core system.
The graph shows temperature above the line, GPU in blue, CPU in green and load per-cent below the line - GPU in orange, CPU in brown.
You can see the moment my game ended (seven minutes out), shortly followed by exiting to Windows.
Anyone experiencing issues should definitely consider poor cooling as a cause.