How to efficiently retrieve data from a C file

I have a program that needs to extract (on startup) data from a text file. This file can get huge and I was wondering how I can speed up the process and evaluate its current performance. The code used to retrieve the data is as follows:

void startUpBillsLoading(Bill *Bills)
{
    FILE *BillsDb = 0, *WorkersDb = 0, *PaymentDb = 0;
    BillsDb = fopen("data/bills.db", "r");
    WorkersDb = fopen("data/workers.db", "r");
    PaymentDb = fopen ("data/payments.db", "r");
    char *Buffer = malloc (512);

    if (BillsDb && WorkersDb && PaymentsDb)
    {
        int i = 0, j = 0;

        while (fscanf (BillsDb, "%d;%[^;];%[^;];%[^;];%[^;];%d/%d/%d;%d/%d/%d;%d;%f;%f\n",
                &Bills[i].Id,
                Bills[i].CompanyName,
                Bills[i].ClientName,
                Bills[i].DepartureAddress,
                Bills[i].ShippingAddress,
                &Bills[i].Creation.Day,
                &Bills[i].Creation.Month,
                &Bills[i].Creation.Year,
                &Bills[i].Payment.Day,
                &Bills[i].Payment.Month,
                &Bills[i].Payment.Year,
                &Bills[i].NumWorkers,
                &Bills[i].TotalHT,
                &Bills[i].Charges) == 14)
        {
            Bills[i].Workers = 
                malloc (sizeof(Employee)*Bills[i].NumWorkers);

            fscanf (PaymentDb, "%d;%d;%[^;];%[^;];%[^\n]\n",
                    &Bills[i].Id,
                    &Bills[i].PaymentDetails.Method,
                    Bills[i].PaymentDetails.CheckNumber,
                    Bills[i].PaymentDetails.VirementNumber,
                    Bills[i].PaymentDetails.BankName);

            LatestBillId++;
            i++;
        }

        i = 0;
        while (fscanf (WorkersDb, "%d;%[^;];%[^;];%f\n",
                    &Bills[i].Id,   
                    Bills[i].Workers[j].Surname,
                    Bills[i].Workers[j].Name,
                    &Bills[i].Workers[j].Salary) == 4)
        {
            for (int j = 1; j <= Bills[i].NumWorkers-1; j++)
            {
                fscanf (WorkersDb, "%d;%[^;];%[^;];%f\n",
                                &Bills[i].Id,   
                                Bills[i].Workers[j].Surname,
                                Bills[i].Workers[j].Name,
                                &Bills[i].Workers[j].Salary);
            }
            i++;
        }

        fclose(BillsDb);
        fclose(WorkersDb);
        fclose(PaymentDb);
    }
    else
        printf ("\t\t\tImpossible d'acceder aux factures !\n");

    free (Buffer);
}

      

        
        
        
      

    

I used a library time.h

to measure the time it takes to get all the data I need. The ticket data is split into 3 files: bills.db, workers.db and payments.db. Each line of the file from bills.db

and from payments.db

represents a complete invoice, whereas the workers.db

number of lines required to represent an invoice is variable and depends on the number of employees associated with the bill.

I created these 3 files this way:

• bills.db
  
  and payments.db
  
  has 118087 lines (thus how many accounts)
• Each account was set (arbitrarily) to have 4 workers, so the file workers.db
  
  has 118087 * 4 = 472348 lines.

The time it takes for this function to run fully is about 0.9 seconds. How good (or bad) is this time and how to improve it?