OS: Windows 10.0.15063 Build 15063
Visual Studio: 2017 15.3.5
Visual Micro: 1709.6.0 free.

It may be that I have not read all the documentation, but I did not understand what the selection of DEBUG or RELEASE, in the control bar, does, since:

1- Compilation is always done with the -Os flag;
2- For example, if you put -O3 in [VisualMicro-Project Properties] extra-flags, they are valid both for the DEBUG and RELEASE options;

In fact I did not find the option of inserting different flags for the two modes;
If it is so, I suggest:
1- Duplicate extra flag lines in [VisualMicro-Project Properties];
or
2- Use the [VisualStudio-Project Properties]: C ++ panels for all the compilation parameters
(General, Optimization ...), leaving everything in the [VisualMicro-Project Properties] all what that concerns the environment.

Years ago I developed the extension in VisualStidio 2012 for Microchip PICs;
  now I went to Arduino and VisualMicro is doing very well (I'm old to reinvent the wheel).
Thank you.

amelia

Thanks for the post and sorry for the delay.

Ignore tools>options. These settings simply control when visual micro will work or when it will leave Visual Studio C++ to compile the project. You need to leave the options empty.

The Visual Studio project property pages are for intellisense only.

When building we use the boards.txt and platform.txt provided with the hardware core to determine build commands this is how the arduino ide works and why we are compatible with arduino.

The Visual micro project properties have extra flags either for project global or for the current "configuration" such as DEBUG/RELEASE. It sounds like the extra flags > "configuration" might help you. 

The arduino core has optimization hard coded for each board. I will add to the to do list to try to give some future options but the arduino design does not support your request.

There is a relatively new feature in visual micro which allows you to override the hardware core build commands. However this feature is not ideal for your request because it is not configuration specific but I will look at a short term change to support that. Try it anyway because you might find it is acceptable for the short term.

Switch on vmicro>compiler>show build properties. Then build and in the output you will see the .c, .cpp and objcopy (elf) commands.

Create a board.txt in the local project and add any commands that you want to override. Then click save on board.txt and build.