Fortunately, this was a known issue. The device needed a BIOS update.
Strangely enough, ASUS does not offer its BIOS for download in their page, so I had to fish out the link in another discussion forum. I mailed them prior to that, so I'm curious to see what's their official answer.
The thing works much better now. Now to see at what speed I can make MegaMameCE3 run Money Puzzle Exchanger [probably not, since it's a small neogeo game, but it must require a lot of RAM/CPU anyway]. :-)
[download a life]