When I use a relative path for the executable's path (either in the games.js, or directly in the command line), it seems the game runs as fast as I can (between 400 and 1900 fps, depending of my computer's settings and whether I run it in fullscreen mode or not).
I tried with perfect cherry blossom, using the following command : thcrap_loader.exe en-fr.js ./Th07.exe (everything is in the current directory)
And the game runs correctly when I use the following command : thcrap_loader.exe en-fr.js "C:/Users/liron_b/Desktop/Touhou 07 - Perfect Cherry Blossom/Th07.exe"
The same bug happens on my other computer. I only tried with Windows 7.