Working on development of a huge project (>300 dll = total 129 Mo), is there
a way to avoid loading of all the pdbs when launching a debug session. One
idea should be  to load pdb only on purpose at runtime when you step into a
given DLL. Another should be to "hide" the pdb in a directory different from
the one of the exe and dll to avoid the implicit load of pdb .

Thanks in advance

If you implicitly link with dlls then it means the exe will need the dll's
at startup, which means the de{*filter*} will be loading the symbols. The
Output window displays this. If you perform a delay load or explict
LoadLibrary then the symbols won't get loaded. I don't there is a setting
in VC++ to defer loading of symbols. WinDBG has an options,
View->Options->Symbols, you can select Defer Loading Until Needed, it might
help.