In the days when people used to race bog standard cars, or as near as dammit, radically increasing the tyre pressures was usually part of the race tune.
Crossply tyres in particular distort and squirm under cornering pressure, and raising the pressures reduced the sloppy feel of cars that heaven knows weren't usually adapted for that sort of thing. In the dry, provided the dampers were working properly, grip was increased and handling made more predictable, at the expense of a more sudden loss of grip when it finally went. They squealed less when they were hard too.
My impression is that modern radials are less affected by these differences, but they certainly will be affected by them and I would think higher pressures would be more economical. But not very much unless you are one of the very many cars I see with visibly - i.e. very - too-soft tyres. One in five or ten in London at a rough estimate.
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