Frank Winklmeier authored Jan 29, 2018 and Brad King committed Jan 30, 2018

For large number of targets significant amount of time is spent in
cmLocalGenerator::FindGeneratorTargetToUse, which uses find_if on a
vector to locate the given target. Using a map instead of vector for
ImportedGeneratorTargets (as done for cmMakefile::ImportedTargets)
provides a significant speedup (up to factor of 2).