[FEA]: Investigate remaining performance issues with PSTL algorithms

[miscco]

Is this a duplicate?

• I confirmed there appear to be no duplicate issues for this request and that I agree to the Code of Conduct

Area

libcu++

Is your feature request related to a problem? Please describe.

Some of the PSTL algorithms show minor performance regressions compared to thrust algorithms.

Describe the solution you'd like

We should investigate where those performance differences come from and see whether we can avoid them.

Some are certainly due to the usage of 64 bit indices which thrust avoids

Describe alternatives you've considered

No response

Additional context

No response

[bernhardmgruber]

I also have the following in my notes:

• Implement parallel cuda::std::copy_if #7518 (comment)
• Implement parallel cuda::std::transform_reduce #7688 (comment)
• Implement parallel cuda::std::unique #8048 (comment)