[R-pkg-devel] Slow down in R 4.2.x

[Johannes Ranke]

Dear list,

independent of the thread on this list about slow examples on R 4.2 on windows 
I have discovered over the last few days that some of my benchmarks (look for 
t4 and t9) run by a factor of 3 slower on R 4.2.x than on R 4.1.3 [1].

This is on Linux, using my own backported R packages for R 4.2.x and locally 
compiled versions (with default configure options) of R-4-1-branch on two 
different CPUs. The results for R 4.2.1 are only slightly modulated by the use 
of different BLAS version (openblas-serial versus atlas versus lapack).

I also tested the R 4.0.4 version that is part of Debian bullseye, it is as 
fast as the locally compiled R 4.1.3.

I went through the NEWS for R 4.2.0 (because the first slow results were 
obtained using that version), but the only change I could imagine causing such 
a change is the additional check of the length of the arguments && and ||.

Any other thoughts?

Johannes

[1] https://pkgdown.jrwb.de/mkin/articles/web_only/benchmarks.html#results 



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