R devel - Jul 2021 - speed of cor(..., use="pairwise.complete.obs") when no NAs are present.

Hello,

I was iterating over some matrices with cor(x, use=?pairwise.complete.obs?) to
handle cases with NA values and noticed that such ?use=? setting had a big
influence on speed even for matrices that had no NAs. Given that anyNA(x) is so
quick, maybe in the case of use=?pairwise.complete.obs? it would make sense to
first check if the arguments have any NAs, and switch to use=?everything? in
such cases?

Below are my quick benchmarks.

x <- matrix(rnorm(1e6), ncol=1e3)

system.time(cor(x))
#    user  system elapsed
 #  0.636   0.003   0.641

system.time(cor(x, use="pair"))
#    user  system elapsed
#   3.509   0.013   3.538

system.time(anyNA(x))
#    user  system elapsed
#  0.001   0.000   0.001


Warm regards,
Karolis K.