BSP Loader Part6: Low FPS when compiling with MinGW

[Deleted user]

If I run executable downloaded from here (github), it works perfectly at 60 FPS, but if I compile it on my laptop with MinGW, it runs only at 30 FPS.
I am using this command:
g++ *.cpp -o Test.exe -L. -ljpeg -llibc -lopengl32 -lglu32 -lwinmm -lgdi32 -mwindows
(It writes much warnings, but I get the executable Test.exe)
Code is exacly the same as here
Can I do it better to get more FPS? What am I doing wrong?