If you have hot loops with millions of iterations at a time, structure your code accordingly. Its not anti-OO to choose the right data structure for the job.

And avoid moving said data between physical threads as much as possible.

Most of the bottlenecks I see are not due to the organization of data. Unnecessary communication of data is the #1 offender.

Maybe someone can write an OO language where arrays of structs are automatically stored as structs of arrays.

mild /s