As the owner of the P: It's certainly not worth the extra money. Unless, as I have stated before, you really like entirely pointless little spoilers. However it is in keeping with the car industry: Mercedes AMG models (not AMG line) and BMW M series (not M sports) cars always offer slightly improved performance but for vastly inflated prices.
I think in general, the none performance models are always the more sensible options to take, you never get bang for your buck with the performance but some people are sad enough (me included) to want the best of the best of the best. So I went for the P.
My bigger issue is why the P (Y) exists at all: The LR is plenty fast enough for everyone and if you really want to pay £10 grand extra for small performance increases then there is no logic at all to buying the heavier, less aerodynamic and therefore slower and less efficient Model Y when the Model 3 performance still exists.