Reading into SBUF is SLOW

# include <stdio.h>

# include <aduc842.h>

#pragma registerbank(2)



void sendmoduleinit(void);
void InitByte_Char (volatile unsigned long);
void print2uart_hex(int);
void displaytemp1(void);

void displaycal(void);
void sendremaining(void);
volatile unsigned char moduleinit;



int ucRxChar1;

int check_sum;
int check_sum_tx;



void main()

{

EA = 1;
ES = 1;

T3CON = 0x83;

T3FD = 0x2D;

SCON = 0x50;


if(ucRxChar1 == 0xCC)

{
sendmoduleinit();
}
if (ucRxChar1 == 0xFA && ucRxChar1 == 0xFA && ucRxChar1 == 0x05 && ucRxChar1 == 0xAA && ucRxChar1 == 0x2F)


{displaytemp1();

}

if (ucRxChar1 == 0x05 && ucRxChar1 == 0xAB)


{displaycal();

}



}

void ISR_sc(void) interrupt 4 using 2

{
if (TI==1) {
TI=0; //clear interrupt
}
else {
ucRxChar1 = SBUF; //put value on pins
RI=0; //clear interrupt
}



/*REN = 1;
while(RI == 0)
                {}

                        ucRxChar1 = SBUF;
                                RI = 0;
*/
}

void sendmoduleinit(void)
{

                                        check_sum = (0xF5 ^ 0xF5 ^ 0x06 ^ 0xFF ^ 0xFF);

                                        check_sum_tx = (check_sum & 0x7F);

                                InitByte_Char(0xF5);
                                InitByte_Char(0xF5);

                                InitByte_Char(0x06);
                                InitByte_Char(0xFF);


                                InitByte_Char(0xFF);

                            print2uart_hex(check_sum_tx);


        }

void InitByte_Char (volatile unsigned long result)

{       REN = 0;
SBUF = result;

                while (TI == 0)
                         {

                         }
                 TI = 0;
 REN = 1;
}
void print2uart_hex(int chksum)
{  REN = 0;

                          SBUF = chksum;
              while (TI == 0)
                         {
                         }
                 TI = 0;
REN = 1;

}

        void displaytemp1(void)
{

                                check_sum =(0xA0 ^ 0xE2 ^ 0x07 ^ 0x00 ^ 0x62 ^ 0x00);

                                check_sum_tx = (check_sum & 0x7F);

                                InitByte_Char(0xA0);
                                InitByte_Char(0xE2);

                                InitByte_Char(0x07);
                                InitByte_Char(0x00);

                                sendremaining();
                                //InitByte_Char(0x62);
                        //      InitByte_Char(0x00);


                           // print2uart_hex(check_sum_tx);


}

void sendremaining(void)
{
InitByte_Char(0x62);
InitByte_Char(0x00);

print2uart_hex(check_sum_tx);

}


void displaycal(void)
{

                                check_sum =(0xA0 ^ 0xE2 ^ 0x07 ^ 0x00 ^ 0x25 ^ 0x00);

                                check_sum_tx = (check_sum & 0x7F);

                                InitByte_Char(0xA0);
                                InitByte_Char(0xE2);

                                InitByte_Char(0x07);
                                InitByte_Char(0x00);


                                InitByte_Char(0x25);
                        InitByte_Char(0x00);


                           print2uart_hex(check_sum_tx);

}