I suggest to use the svn mirror github *only* if there is no working git client for the system one is using. Even for "Read only" users: git is normally faster and a git working copy takes less space.
Maybe on *nix, but on Windows, git is much slower IMHO.
Just tested (Windows 10 Pro, NVM SSD), so it's really your IMHO:
c:\fpc\tmp>fptime svn co -q
https://github.com/fpc/FPCSource/trunk89347.000 ms
c:\fpc\tmp>fptime git clone
https://github.com/fpc/FPCSource.gitCloning into 'FPCSource'...
remote: Enumerating objects: 665421, done.
remote: Counting objects: 100% (2234/2234), done.
remote: Compressing objects: 100% (706/706), done.
remote: Total 665421 (delta 1688), reused 2035 (delta 1524), pack-reused 663187
Receiving objects: 100% (665421/665421), 166.06 MiB | 5.22 MiB/s, done.
Resolving deltas: 100% (535772/535772), done.
Updating files: 100% (20103/20103), done.
51129.000 ms