[SOLVED] detecting these delays in ISR execution ( "interrupt latency" )

#define _XTAL_FREQ 8000000

// PIC18F45K80 Configuration Bit Settings
// CONFIG1L
#pragma config RETEN = OFF      // VREG Sleep Enable bit (Ultra low-power regulator is Disabled (Controlled by REGSLP bit))
#pragma config INTOSCSEL = HIGH // LF-INTOSC Low-power Enable bit (LF-INTOSC in High-power mode during Sleep)
#pragma config SOSCSEL = HIGH   // SOSC Power Selection and mode Configuration bits (High Power SOSC circuit selected)
#pragma config XINST = OFF      // Extended Instruction Set (Disabled)

// CONFIG1H
#pragma config FOSC = INTIO2    // Oscillator (Internal RC oscillator)
#pragma config PLLCFG = OFF     // PLL x4 Enable bit (Disabled)
#pragma config FCMEN = OFF      // Fail-Safe Clock Monitor (Disabled)
#pragma config IESO = OFF       // Internal External Oscillator Switch Over Mode (Disabled)

// CONFIG2L
#pragma config PWRTEN = OFF     // Power Up Timer (Disabled)
#pragma config BOREN = SBORDIS  // Brown Out Detect (Enabled in hardware, SBOREN disabled)
#pragma config BORV = 3         // Brown-out Reset Voltage bits (1.8V)
#pragma config BORPWR = ZPBORMV // BORMV Power level (ZPBORMV instead of BORMV is selected)

// CONFIG2H
#pragma config WDTEN = OFF      // Watchdog Timer (WDT disabled in hardware; SWDTEN bit disabled)
#pragma config WDTPS = 1048576  // Watchdog Postscaler (1:1048576)

// CONFIG3H
#pragma config CANMX = PORTB    // ECAN Mux bit (ECAN TX and RX pins are located on RB2 and RB3, respectively)
#pragma config MSSPMSK = MSK7   // MSSP address masking (7 Bit address masking mode)
#pragma config MCLRE = ON       // Master Clear Enable (MCLR Enabled, RE3 Disabled)

// CONFIG4L
#pragma config STVREN = ON      // Stack Overflow Reset (Enabled)
#pragma config BBSIZ = BB2K     // Boot Block Size (2K word Boot Block size)

// CONFIG5L
#pragma config CP0 = OFF        // Code Protect 00800-01FFF (Disabled)
#pragma config CP1 = OFF        // Code Protect 02000-03FFF (Disabled)
#pragma config CP2 = OFF        // Code Protect 04000-05FFF (Disabled)
#pragma config CP3 = OFF        // Code Protect 06000-07FFF (Disabled)

// CONFIG5H
#pragma config CPB = OFF        // Code Protect Boot (Disabled)
#pragma config CPD = OFF        // Data EE Read Protect (Disabled)

// CONFIG6L
#pragma config WRT0 = OFF       // Table Write Protect 00800-01FFF (Disabled)
#pragma config WRT1 = OFF       // Table Write Protect 02000-03FFF (Disabled)
#pragma config WRT2 = OFF       // Table Write Protect 04000-05FFF (Disabled)
#pragma config WRT3 = OFF       // Table Write Protect 06000-07FFF (Disabled)

// CONFIG6H
#pragma config WRTC = OFF       // Config. Write Protect (Disabled)
#pragma config WRTB = OFF       // Table Write Protect Boot (Disabled)
#pragma config WRTD = OFF       // Data EE Write Protect (Disabled)

// CONFIG7L
#pragma config EBTR0 = OFF      // Table Read Protect 00800-01FFF (Disabled)
#pragma config EBTR1 = OFF      // Table Read Protect 02000-03FFF (Disabled)
#pragma config EBTR2 = OFF      // Table Read Protect 04000-05FFF (Disabled)
#pragma config EBTR3 = OFF      // Table Read Protect 06000-07FFF (Disabled)

// CONFIG7H
#pragma config EBTRB = OFF      // Table Read Protect Boot (Disabled)

// #pragma config statements should precede project file includes.
// Use project enums instead of #define for ON and OFF.

#include <xc.h>

__bit timeFlag = 0;
//volatile int timeFlag = 0;
volatile unsigned char seconds = 0;


// Calculate Reload_Value for 1ms with a 20 MHz oscillator and prescaler 8
#define Reload_Value 625 // (20,000,000 XTAL / 4 / 8 prescale) = 625

void initializeTimer1() {
    // Configure Timer1 in 8-bit mode with a prescaler of 8
    T1CON = 0b00110000; // mode 0x08 interrupt, CCP1 pin hi on ==

    // Configure CCP module
    // CCP1CON = 0b00001011; // 0x0B
    CCP1CON = 0b00001000; // 0x08
  
    // Load the high and low bytes of Reload_Value into CCPR1
    CCPR1 = Reload_Value;
   // CCPR1H = (Reload_Value >> 8); // Load high byte of Reload_Value
   // CCPR1L = (Reload_Value & 0xFF); // Load low byte of Reload_Value

    // Clear Timer1 registers
    TMR1H = 0;
    TMR1L = 0;

    // Clear Timer1 interrupt flag
  //  TMR1IF = 0;
    // Clear CCP1 interrupt flag
    CCP1IF = 0;
  
    // Start Timer1 and CCP module
    TMR1ON = 1;
    CCP1IE = 1; // Enable CCP1 interrupt
}

void main() {
    // Initialize Timer1
    initializeTimer1();

    // Initialize INTCON register
    INTCON = 0; // Clear INTCON register
  
    // Enable global and peripheral interrupts
    INTCONbits.PEIE = 1; // Peripheral Interrupt Enable
    INTCONbits.GIE = 1;  // Global Interrupt Enable

    while (1) {
        // Check if the timeFlag is set (1ms interval)
        if (timeFlag) {
            // Increment seconds
            seconds++;

          
            // Reset the timeFlag to indicate that the 1ms interval has been processed
            timeFlag = 0;
        }
    }
}

void __interrupt() ISR() {
    if (CCP1IF){     
               // Clear the CCP1 interrupt flag
        CCP1IF = 0;
                // advance COMPARE value
        CCPR1 += Reload_Value;
      
        timeFlag = 1;    // Notify main routine
    }
}