Hi,
The binary size explains the delay. You can add a custom post-build step to deploy your binary and disable the automatic deployment in Debug settings. As the build process always runs in the background, this will move the deployment to the background as well.
Regarding “searching for a matching source file”, VisualGDB does that when it’s searching for a .cpp file that includes the .h file being opened. Normally it quickly scans all source files for unconditional include directives and picks the first matching one, however if none of the files include your header file unconditionally, VisualGDB will try fully parsing some of the files to find which of them actually includes the header. Is your header directly included from one of the files? Is the include directive surrounded by #ifdef or #if?