I don’t anticipate needing it for now - tomorrow is forecast to be 38C, which I think is hotter than I remember it ever being here. I don’t know what temperature the roof space will get to, but I expect hotter than it was today. If the temperatures remain sensible during normal operation I won’t worry about a heat sink.
The results of the longer run were:
Total time (ms) : 161825 Nodes searched : 90659083 Nodes/second : 560229
and the first shorter run were
Total time (ms) : 83847 Nodes searched : 48088937 Nodes/second : 573531
I didn’t stop any other services running, and the Pi is running at standard speed. Normal CPU usage hovers just under 20% overall.