Is there a faster lm function

Question

I would like to get the slope of a linear regression fit for 1M separate data sets (1M * 50 rows for data.frame, or 1M * 50 for array). Now I am using the lm()

Answer 1

lmfit in the package Rfast is even faster than .lm.fit. The only drawback is that it does not work when the design matrix does not have full rank.