Rikomagic RKM MK902 flv files problem topic

I have a Rikomagic MK902 16 Gb. It works fine, but I have a little problem when I try to see a remote movie whit XBMC. If file is mp4, it plays perfect, but if file is flv, it plays for 3, 4 seconds, then wait a variable amount of time and then plays again for 3, 4 seconds and again the same. I've tried MX Player, BSPlayer, VPlayer and always the same, mp4 files no problem and flv files problem.
My internet conection is 100 Mbps.
Any suggestion????
Thanks.