Hi,
First of all, one time I have done such project. Our task was scrolling text engine via LEDs Dot Matrix (we used 8x8 Kingbright multicolour ones).
Well, first of all: be careful about refresh direction. It is very important. If you do it wrong then scroll text will tremble (visually). For scrolling from right to left do refresh from up to down line-by-line.
Okay, now about hardware. We used simple AT89S8252 at 11.0592 Mhz w/o external RAM/ROM. Such configuration allows us to support 6 matrix device board (48x8 dots).
Boards then are connected in lines.
About refresh rate. If you use time based colour mix (produce yellow as quick flash one time red then next time green) you should switch it about 70 times per second to see really yellow colour. At lower refresh rates I seen red-green flashes.
As for refresh rate for non-blinking mode: it should be above 50Hz and if higher then better. We use 100Hz refresh rate (all the matrixes are refreshed 100 times per second) and it loads MCU time for about 17% - pure assembly, you know (=
So you should raise up refresh rate at least twice (35 and above - it is min. acceptable value).
Good days!