The paper introduces a new R package named fundiversity that updates the famous FD package with parallelization, internal caching of reusable results, and up-to-date good programming practises.

The paper is easy to read and straightforward. Arguments for change are convincing and well-documented.
I have very few comments.

line 105: when I installed fundiversity on my computer, it also installed : ‘listenv’, ‘parallelly’, ‘future’, ‘globals’, ‘magic’, ‘lpSolve’, ‘linprog’, ‘RcppProgress’, ‘future.apply’, ‘geometry’. More precisely,
miniCRAN::pkgDep(pkg = "fundiversity", suggests = FALSE)
returns 23 dependencies, which is pretty good but more than I understood when I read lines 105-106.
plot(miniCRAN::makeDepGraph(pkg = "fundiversity", suggests = FALSE))
shows them.
Please rewrite the end of the paragraph. Maybe you should argue that your first-level dependencies have a wide-enough audience to ensure they will be maintained in the log term.

line 137 : the command "data(..., package = "fundiversity")" is confusing because you use "..." for while "..." is an argument in R functions. Moreover, thanks to lazy loading, data() is useless: your code works without the first two lines of the code chunk starting after line 143. Please rewrite.

line 140: this code chunk should be hidden (echo = FALSE ).

line 159: I'm not sure ecologists are familiar with Z-score. Be more explicit, e.g. add "so that their mean is 0 and their standard deviation is 1".

line 163: I don't understand "We can then compute the functional richness of each index at each location". I guess you meant "We can then compute the functional richness at each location".

Last, nothing is said in the case study section about how to use future::plan(). A good introduction is in the "parallel" vignette: repeat it in the paper.

The authors addressed my comments. I think the paper is ready for publication.