Lag in RSSI refreshing

Hi.

I am using:
Bluno Nano Arduino BLE Bluetooth
Arduino IDE 1.8.7 for Windows

I am interested in reading the RSSI value in real-time to use as a distance estimation. However, I am finding that there is a very significant lag in the RSSI value being updated. For example, when the paired device is very close it will read -41 but when I move the paired device far away it will continue to read -41 for many seconds (10-90 seconds) before it gets updated to another value such as -77. If I move closer again it will continue to say -71 for many seconds until it starts reporting the stronger signal strength. Is this simply a limitation of the Bluno device? Thanks.

My program below.

char Data[100];
char RAW[3];
int INDEX;

void setup() {
Serial.begin(115200); //Initiate the Serial comm
Serial.println("In Setup");
}


void loop(){
int x=0;

delay(500);
Serial.print("+");
Serial.print("+");
Serial.print("+");
delay(500);

for(x=0 ; Serial.available() > 0 ; x++ ){ // get the Enter AT mode words
Data[x] = Serial.read(); // Read and store Data Byte by Byte
}

Serial.println("AT+RSSI=?"); // Ask about the RSSI
delay(500);

for( ; Serial.available() > 0 ; x++ ){
Data[x] = Serial.read(); // Read and store Data Byte by Byte
}

Serial.println("AT+EXIT");
delay(500);

int last_byte = x;

//Serial.print("after AT exit, x=");
//Serial.println(x);

for( x=0; x <= last_byte; x++ ){
Serial.print(Data[x]);
}
Serial.println();
}