Speed improvements

[kevinushey]

Although the current implementation of attributes::compileAttributes() is certainly 'fast enough', we're still about half the speed of Rcpp::compileAttributes(). There are surely some low hanging fruit; e.g. using timeit to profile:

plot(timeit(attributes::compileAttributes()))

gives the plot

I can only imagine some of this slowness is related to e.g. unnecessary repeated reading of files, or lack of vectorization.

[romainfrancois]

Thanks for looking into this.

[romainfrancois]

Which codebase to you use for the benchmarks ?

[kevinushey]

I've been using my own package Kmisc which has a mess of C++ files: https://github.com/kevinushey/Kmisc

I'm not sure how good a job timeit is doing here though -- after removing file existence checks, the rest of the time is actually in .Calls so my (overly conservative, probably slow) C/C++ code is probably the culprit.