On initial contribution to the gnu binutils project, the Google developer for Gold claimed a 5x speed improvement: https://sourceware.org/pipermail/binutils/2008-March/055660....
In a public talk on llvm lld, the Google developer for LLD claimed another 5x speed improvement:
https://llvm.org/devmtg/2017-10/slides/Ueyama-lld.pdf