Peter Solymos has an update to his pbapply library:
The pbapply R package that adds progress bar to vectorized functions has been know to accumulate overhead when calling
parallel::mclapplywith forking (see this post for more background on the issue). Strangely enough, a GitHub issue held the key to the solution that I am going to outline below. Long story short: forking is no longer expensive with pbapply, and as it turns out, it never was.
H/T R-Bloggers