You are right - glob is slower than readdir.
My point is the short one-liner. Otherwise:

# time ls | wc -l
99999

real    0m1.850s
user    0m1.590s
sys     0m0.210s


# time perl -e '@_ =  glob"*";print$#_'
99998

real    0m1.462s
user    0m0.880s
sys     0m0.570s

# the best alternative:
# time perl -MIO::Dir -e '@_ = IO::Dir->new(".")->read;print$#_'
100000
real    0m0.680s
user    0m0.570s
sys     0m0.100s
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