Thanks for the report, can you enable all options shown at the top of the page and send us the build output for both scenarios?

Thanks for the clear info. We will look into it but the issue is probably related to the fact you have enabled the "build in intermediate folder" via tools>options>vmicro>compiler? 

That shows in the build output as:-
vm.runtime.build.intermediate_output_path= [Path .......]
vm.runtime.build.intermediate_output_enabled=true

The best solution is the default, which uses "shared core cache". Then each core is strictly cached on the compiler settings.

The build in intermediate and "standard build without shared core cache" should indeed dump the cache and rebuild the core in your example. We will fix that but it is much faster to use the "shared core cache". Please try it.

Thanks

Yes that works well, the default settings cover that common scenario. The cache is designed for that and the default Visual Micro settings are optimal. 

The same board can use the same or different options in multiple projects. It is not something that users would normally need to consider. 

Arduino always works in both the Arduino IDE and Visual Micro allow the same or different pojects to use any combination of settings. The Arduino IDE will rebuild the core more often, it only uses a single core cache per IDE instance. The default for Visual Micro is to use a different core cache for each set of settings. 

Bear in mind that the build of the core is entirely unrelated to project and library code. It is always seperate. Therefore the same core with the same build settings can cleanly be shared between different projects when/if required.

Make sure that you have not switched off "vMicro>Compiler>Shared Cache For Cores". This will give the best experience and is the default setting. It will avoid rebuilding the core when build options are changed to a previously used set.