Split a Visual Studio C++ project : how to do it (almost) automatically?

I have a Visual studio 2015 C++ project that has references to a few 3rd-party free library. Just to reduce compile time (currently 5 - 90 seconds), I want to split the project into many smaller projects. In preparation, I have already created filters in the solution explorer. The filters show a top-level structure of my project - divided into tier :- Tier 1 - my core library, no reference to outside, rarely change Tier 2a - my custom encapsulator for external library "A" Tier 2b - my custom encapsulator for external library "B" ... note: all Tier2 #include Tier1 , rarely change Tier 3 - business logic that rarely change, #include Tier1&2 Tier 4 - business logic that often change , #include Tier1&2&3 Question : How to split this project into many projects easily? e.g. almost easy as click a filter then select "extracted to a new project" I have read some sources - their explanation suitable for how to create from scratch, not for an existing project. It also seems that I have to add some lines for some individual files. #if defined DLL_EXPORT #define DECLDIR __declspec(dllexport) #else #define DECLDIR __declspec(dllimport) #endif I have >100 files, so it is not very practical. I googled "split visual studio c++ project", but did not find many results. Relate question : not explain "how"How do you split a Visual Studio Solution? External link : all has the line #define DECLDIR __declspec(dllexport)http://www.codeguru.com/cpp/cpp/cpp_mfc/tutorials/article.php/c9855/DLL-Tutorial-For-Beginners.htmhttps://manski.net/2011/11/creating-a-dll-project/