Lardy
If you think Heathrow is the busiest airspace in the world, I suggest you are not very well travelled
Heathrow oft touts itself as the busiest international airport in the world, possibly still true, but that is only because a high proportion of flights are international due to the nature of island Britain! People construe that to mean it is the busiest airport in the world - far from true.
As to airspace and trafiic levels, I suggest you look west towards NYC, Chicago, Atlanta, Los Angeles etc etc all with many IFR approaches to multiple airports within sometimes very constrained airspace due to terrain. Heathrow may maximise the runways it has, but is relatively simple compared to some of the above.
That is not to doubt that high winds, especially down the runway axis have dramatic effects at LHR where the runways operate at 98% capacity.