iLiad Refresh display immediately on Iliad

[illiad_fan]

Hi all,
I'm writing a Whiteboard program(C language) on Iliad. I used the

dmDisplay(dmCmdPriorUrgent, dmQTyping);

for refreshing the display after each drawing. But the refresh speed is low(delay about 0.5s) than my expecting so much. I found that iPDF refresh immediately and I'm reading its source code, but not find solution yet.
Is there any one know the solution? Please help me!