no (proper) midi playback when using SD card

When I install the nyan-cat package to the SD card on a flow3r-firmware v1.2.0 then after starting the app I only see the animation but I have no sound. Closing the app via the right shoulder button closes the animation and makes the audio playback start.

When installing the package to flash then midi playback is working, though quite slowly. Reverting "f7499a35 draw nyancat images" makes the audio work from the SD card too (but disables the animation).