Proposed minimal patch implements globbing in pathlib using os.scandir(). Here are results of microbenchmarks:

$ ./python -m timeit -s "from pathlib import Path; p = Path()" -- "list(p.glob('**/*'))"
Unpatched: 598 msec per loop
Patched:   372 msec per loop

$ ./python -m timeit -s "from pathlib import Path; p = Path('/usr/')" -- "list(p.glob('lib*/**/*'))"
Unpatched: 1.33 sec per loop
Patched:   804 msec per loop

$ ./python -m timeit -s "from pathlib import Path; p = Path('/usr/')" -- "list(p.glob('lib*/**/'))"
Unpatched: 750 msec per loop
Patched:   180 msec per loop

See msg257954 in issue25596 for comparison with the glob module.