There's little paradoxical about it.. if you link against 20 DLLs, that turns into 20 directory lookups and then random paging potentially across the entire drive, whereas a .EXE is more likely to appear contiguously on the drive, and after the first page of it is loaded in, the OS readahead mechanism might opportunistically snarf something like the next 256kb worth of pages for free as part of the same IO.

Ignoring IO, and depending on the size of the app (particularly C++ apps though), the linker might be spending a huge amount of time on symbol fixups.