 work will by far overwhelm any parallel speedup.
Also data.table itself already seems to exploit some thread-level parallelism (one often sees user time &amp;gt; elapsed time).
Requires the parallel package.  For a worked example with significant speedup please see https://github.com/WinVector/rqdatatable/blob/master/extras/Parallel_rqdatatable.md."><!-- mathjax --><script src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/MathJax.js" integrity="sha256-nvJJv9wWKEm88qvoQl9ekL2J+k/RWIsaSScxxlsrv8k=" c