Feather is file format designed for efficient on-disk serialisation of data frames that can be shared across programming languages (e.g. Python and R).

library(feather)
write_feather(mtcars, "mtcars.feather")
mtcars2 <- read_feather("mtcars.feather")

Install the released version from CRAN:

# install.packages("feather")

Or the development version from GitHub:

# install.packages("devtools")
devtools::install_github("wesm/feather/R")