[BUILDING.md] Update GNU/Linux Speeding up section

[congzhangzh]

1. C/C++ link is slow, especially for node like project, which will link GBs data to 100MB like size
2. C/C++ link process can not be cached
3. mold is really really fast

[congzhangzh]

@targos @rvagg @jasnell @refack @Trott Hi folks, can you do a doc review? or cc to others if needed:)

/cc @nodejs/build

[Trott]

@nodejs/build

I don't think we want to recommend or document mold unless core team members are already using it.

[H4ad]

I give it a try and it seems to reduce my build time from 17s to 10s while using ccache after compiling it once.

Without ccache, I didn't see any significant change in the build time.

[congzhangzh]

I give it a try and it seems to reduce my build time from 17s to 10s while using ccache after compiling it once.

Without ccache, I didn't see any significant change in the build time.

@H4ad hi, have you remove out dir completely before you do link speed comparison? As node c++ part is small compared to other third party.

[H4ad]

@congzhangzh Of course, I also tried switching between clang and g++ and I didn't see significant changes in build time with or without mold.

But in any case, mold looks promising and it didn't break the builds locally, if you want to land this change, I can approve if you rename your commit/pr to something like: doc: add mold to linux speeding up section to match the guidelines.

Also, remove the commit/changes related to Windows, this can be a separated PR.

[congzhangzh]

@congzhangzh Of course, I also tried switching between clang and g++ and I didn't see significant changes in build time with or without mold.

But in any case, mold looks promising and it didn't break the builds locally, if you want to land this change, I can approve if you rename your commit/pr to something like: doc: add mold to linux speeding up section to match the guidelines.

Also, remove the commit/changes related to Windows, this can be a separated PR.

@H4ad Cool, I will split this part into another pull request!

BTW, I want to try to verify the mold again, as your machine is super fast, my machine is a little slow and has less memory
The link problem is a nightmare when I do some Chromium development and some other heavy C++ projects, I will be back later!

[congzhangzh]

@H4ad Hi Vinicius,

speed-related pull request is created: #52179
windows build failed related pull request is created: #52181