The timing sample, TIMEWING.EXE, found in the SAMPLES\TIMEWING subdirectory of the WinG development kit, times and compares the blt and stretching speeds of StretchBlt, StretchDIBits, and WinGStretchBlt. The application provides a summary you can use to compare the speeds of these techniques on various video configurations and a framework you can use for your own timing tests.
Note that StretchDIBits and WinGStretchBlt operate on device-independent bitmaps whereas StretchBlt and BitBlt operate on device-specific bitmaps, which require no translation and can sometimes be stored in the local memory of the graphics card itself.
Timewing.exe can be built as a Win32 app by compiling with the timewing.m32 makefile. You may need to modify timewing.m32 for your compiler environment.