We could make various changes to use the modularized build more effectively (e.g. not passing the full paths to every single library). But we effectively dump all VTK_LIBRARIES to the linker anyway, so modularization was kind of a no-op and comes at the cost of startup time. Processing >600 dynamic libraries is really slow on mac (and to a lesser degree linux): a debug build takes close to 1 min to start on mac, the majority of which is in strcmp during symbol relocations. Release build is somewhat faster of course, but still spends most time doing relocation.
(Apple’s code dump for 10.13 shows big changes in dyld including some files about “caching”, so maybe this improves in High Sierra – but I still haven’t upgraded)