Given this is a topic of slow c++ builds, mentioning LTCG should come with the caveat that it will absolutely destroy your compile times.
It's also not infallible and you might find it difficult to track a regression if introduced by someone silently breaking a heurestic in the optimiser.
According to MS[0], LTCG doesn't work with /INCREMENTAL (note /LTCG:INCREMENTAL is different). For my use cases, LTCG is unusable for anything other than our overnight builds.
