PERF: Calculate mask in interpolate only once

[phofl]

• closes #xxxx (Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

Gives us an easy 10% speedup

PR: 15.4 ms ± 266 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)
Main: 17 ms ± 69.3 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)

[gfyoung]

LGTM pending CI

[mroeschke]

Thanks @phofl