Send large Data packets from Processing to Arduino

Thanks for reply.
AT the moment I send the Data's as follows:

void geddata(void){
  Serial.flush();
  for(int x=1; x<7; x++){
    Serial.flush();
    Serial.print(x, BYTE);
    for(int i=0; i<4; i++){
      for(int k=0; k<8; k++){
        while(Serial.available()<1){
          ;
        }
        Data[((x-1)*4)+i][k]=Serial.read();
      }
    }
  }
  Serial.flush();
  Serial.print(7, BYTE);
    for(int k=0; k<8; k++){
      while(Serial.available()<1){
        ;
      }
      Data[24][k]=Serial.read();
    }
    Serial.flush();
}

The problem is that the inputbuffer seams like not to be able to manage Data's larger then 40byte, (???) otherwise they get lost somewere in the sistem. So I have to send the Data packets in 7 units what makes the transaction verry slow. It takes about 130ms for the communication that can be 20ms if it were one packet. The main problem is that i try to control a led matrix with my arduino and the datatransfer should not be longer then 41ms to have 24 frame per second.
Does anybody know something about these problem?

PS: My Arduinos are NG