Slight performance regressions in opam update #6561
Description
#5892 fixed a significant number of bugs and issues linked with our use of GNU patch in opam < 2.4.
However this came at a slight cost of performance (about 20% in some cases).
This can be shown in its most egregious form using the following dockerfile:
FROM ocaml/opam
RUN cd opam-repository && git checkout 2025-01-before-archiving-phase1 && rm -rf .git
RUN git clone https://github.com/ocaml/opam
RUN cd opam && git checkout 2.4.0-beta1 && make cold
RUN sudo install ./opam/opam /usr/bin/opam
RUN opam repo set-url default https://opam.ocaml.org
RUN rm -rf .opam/repo/default && mv opam-repository .opam/repo/default
RUN opam update --debug
(simply replace 2.4.0-beta1 by 2.3.0 to show the difference with the latest stable release)
Related to #5896