First, be sure that you cut your data by database grid. Choose size of database grid considering features of your pattern design and uniformity of writing field.
Check on Use Stage control on Exposure tab of Options->Exposure and Video Options dialogue.
Select Subfield Size at exposure on Exposure tab of Options->Exposure and Video Options dialogue. Be sure that your subfield will not exceed total writefield (Options->Exposure and Video Options->Field :: Field Size).
In case you select Subfield Size equal to 1, stage will move after drawing every grid field. The smaller subfield the large number of stage movements and longer the time of writing.