Reactivate Majestical Imperial runs slowly

Reactivate Majestical Imperial (the third Len'en game) runs at approximately 10 FPS. Windows 7 64-bit, DirectX 11. The title screen runs at normal speed (60 FPS if you don't remember, although Ubuntu 14.04 + Wine runs slowly even in the title screen). I've tried various measures:

• Running in Japanese locale
• Running compatibility mode
• Running with 16-bit color
• Running fullscreen

I don't even know if this problem affects the entire game or just Stage 1 This slowdown applies to all stages. Surprisingly enough, running in 256 colors made the slowdown disappear, probably because doing so prevents the background from being drawn.

Evanescent Existence (the first installment), on the other hand, runs fine, except for Stage 5 which runs at only 30 FPS.

Any help would be appreciated.