Longer pipelines on Cortex R's vs real-time & performance

On Cortex M's , you have 3 stage pipelines, while Cortex R's starting from R4 up you have 8 stage, and R7 even 11.

I don't understand, isn't worse for real-time interrupt response to have longer pipelines? I did read that Cortex-R can interrupt long stores/loads, and jump straight to the vector address & the irq number passed, that is great, but doesn't the pipeline get flushed every hw interrupt or exception/fault, and needs to be re-filled with instructions? So more cycles spent.?  And, it's not that the pipeline get saved for return from interrupts..? 

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