Thanks again for the feedback. My latest attempt is the following. I've added the sleep function call back in again to see if it will solve the excessive CPU time problem.

#    This program displays details about console events that occur in 
+the window in
#    wnich this program is running.  This program creates a file calle
+d "event_log.txt"
#    in the current directory.
#
#    References:
#
#           https://docs.microsoft.com/en-us/windows/console/reading-i
+nput-buffer-events
#
#       Definitions and values of constants such as ENABLE_* are avail
+able at the
#       following URL:
#
#           https://docs.microsoft.com/en-us/windows/console/setconsol
+emode
#

BEGIN

    {
        select STDERR;
        $|++;   #   do not buffer STDERR

        select STDOUT;
        $|++;   #   do not buffer STDOUT

        system ("cls");
        print "\n\n\tInitializing the environment ...\n\n\t";
    };

use strict;
use warnings;

use Time::HiRes qw (sleep);

#   The following package provides access to basic information about t
+he runtime environment
#   such as the release of Windows under which this program is running

use Win32;

#   The following package provides access to console events such as ke
+y presses and mouse clicks

use Win32::Console;

my ($IN, $OUT);

my @console_event;
my @info;

my $log_file = "event_log.txt";
my $fh_log_file;

unless (open ($fh_log_file, ">", $log_file))

    {
        print STDERR "\nCould not open $log_file: $!\n\n";
        die;
    }

unless ($IN = Win32::Console -> new (STD_INPUT_HANDLE))

    {
        print STDERR "\nSomething has gone wrong with the Win32::Conso
+le constructor: $!\n\n";
        die;
    }

unless ($OUT = Win32::Console -> new (STD_OUTPUT_HANDLE))

    {
        print STDERR "\nSomething has gone wrong with the Win32::Conso
+le constructor: $!\n\n";
        die;
    }

$IN -> Flush ();

my $starting_console_mode_setting = $IN -> Mode;

END {$IN -> Mode ($starting_console_mode_setting)};

$IN -> Mode ((($starting_console_mode_setting | 0x0010 ) & ~0x0040 ) &
+ ~ENABLE_PROCESSED_INPUT);

print "Perl version $^V running on ", join (" ", Win32::GetOSName), ".
+\n\n";
print $fh_log_file "Perl version $^V running on ", join (" ", Win32::G
+etOSName), ".\n\n";

#   The following is to demonstrate that the $console environment has 
+been set up

print "Your mouse has ", $IN->MouseButtons(), " buttons.\n\n";
print $fh_log_file "Your mouse has ", $IN->MouseButtons(), " buttons.\
+n\n";

print "Enter keyboard activity or mouse events ...\n\n";
print $fh_log_file "Enter keyboard activity or mouse events ...\n\n";

my $start_time = time ();
my $when_to_stop_listening = $start_time + 15;

while (time () < $when_to_stop_listening)

    {
        if ($IN -> GetEvents ())   #   This may be unnecessary, can si
+mply invoke Input ()
                                        #   and check if it has return
+ed anything

            {
                @console_event = $IN -> Input ();

                print "A console event has been detected.  Its attribu
+tes are the following:\n\n";
                print $fh_log_file "A console event has been detected.
+  Its attributes are the following:\n\n";

                print "Time of event:      ", time (), "\n";
                print $fh_log_file "Time of event:      ", time (), "\
+n";
                print "Type of event:      ";
                print $fh_log_file "Type of event:      ";

                if (defined ($console_event [0]))

                    {
                        if ($console_event [0] == 1)

                            {
                                print "Keyboard event.\n";
                                print $fh_log_file "Keyboard event.\n"
+;
                                print "Key down:           ", $console
+_event[1], "\n";
                                print $fh_log_file "Key down:         
+  ", $console_event[1], "\n";
                                print "Repeat count:       ", $console
+_event[2], "\n";
                                print $fh_log_file "Repeat count:     
+  ", $console_event[2], "\n";
                                print "Virtual key code:   ", $console
+_event[3], "\n";
                                print $fh_log_file "Virtual key code: 
+  ", $console_event[3], "\n";
                                print "Virtual scan code:  ", $console
+_event[4], "\n";
                                print $fh_log_file "Virtual scan code:
+  ", $console_event[4], "\n";
                                print "ASCII code:         ", $console
+_event[5], "\n";
                                print $fh_log_file "ASCII code:       
+  ", $console_event[5], "\n";
                                print "ASCII code letter:  ", chr $con
+sole_event[5], "\n";
                                print $fh_log_file "ASCII code letter:
+ ", chr $console_event[5], "\n";
                                print "Control key state:  ", $console
+_event[6], "\n";
                                print $fh_log_file "Control key state:
+  ", $console_event[6], "\n";
                            }

                        elsif ($console_event [0] == 2)

                            {
                                print "Mouse event.\n";
                                print $fh_log_file "Mouse event.\n";

                                print "Mouse X coord:      ", $console
+_event[1], "\n";
                                print $fh_log_file "Mouse X coord:    
+  ", $console_event[1], "\n";

                                print "Mouse Y coord:      ", $console
+_event[2], "\n";
                                print $fh_log_file "Mouse Y coord:    
+  ", $console_event[2], "\n";

                                print "Mouse button state: ", $console
+_event[3], "\n";
                                print $fh_log_file "Mouse button state
+: ", $console_event[3], "\n";

                                print "Control key state:  ", $console
+_event[4], "\n";
                                print $fh_log_file "Control key state:
+  ", $console_event[4], "\n";

                                print "Event flags:        ", $console
+_event[5], "\n";
                                print $fh_log_file "Event flags:      
+  ", $console_event[5], "\n";
                            }

                        else

                            {
                                print "Unknown type \"$console_event[0
+]\".\n";
                                print $fh_log_file "Unknown type \"$co
+nsole_event[0]\".\n";
                            }

                        print "\nAdditional information as of the time
+ of the event:\n\n";
                        print $fh_log_file "\nAdditional information a
+s of the time of the event:\n\n";

                        @info = $OUT -> Info();

                        #   @info contains the following elements:
                        #
                        #   $info[0]:   columns (X size) of the consol
+e buffer.
                        #   $info[1]:   rows (Y size) of the console b
+uffer.
                        #   $info[2]:   current column (X position) of
+ the cursor.
                        #   $info[3]:   current row (Y position) of th
+e cursor.
                        #   $info[4]:   current attribute used for Wri
+te.
                        #   $info[5]:   left column (X of the starting
+ point) of the current console window.
                        #   $info[6]:   top row (Y of the starting poi
+nt) of the current console window.
                        #   $info[7]:   right column (X of the final p
+oint) of the current console window.
                        #   $info[8]:   bottom row (Y of the final poi
+nt) of the current console window.
                        #   $info[9]:   maximum number of columns for 
+the console window, given the current buffer size, font and the scree
+n size.
                        #   $info[10]:  maximum number of rows for the
+ console window, given the current buffer size, font and the screen s
+ize.

                        print "\$info[0]  = ", sprintf ("%6d", $info[0
+]), "\tcolumns (X size) of the console buffer\n";
                        print $fh_log_file "\$info[0]  = ", sprintf ("
+%6d", $info[0]), "\tcolumns (X size) of the console buffer\n";
                        print "\$info[1]  = ", sprintf ("%6d", $info[1
+]), "\trows (Y size) of the console buffer\n";
                        print $fh_log_file "\$info[1]  = ", sprintf ("
+%6d", $info[1]), "\trows (Y size) of the console buffer\n";
                        print "\$info[2]  = ", sprintf ("%6d", $info[2
+]), "\tcurrent column (X position) of the cursor\n";
                        print $fh_log_file "\$info[2]  = ", sprintf ("
+%6d", $info[2]), "\tcurrent column (X position) of the cursor\n";
                        print "\$info[3]  = ", sprintf ("%6d", $info[3
+]), "\tcurrent row (Y position) of the cursor\n";
                        print $fh_log_file "\$info[3]  = ", sprintf ("
+%6d", $info[3]), "\tcurrent row (Y position) of the cursor\n";
                        print "\$info[4]  = ", sprintf ("%6d", $info[4
+]), "\tcurrent attribute used for Write\n";
                        print $fh_log_file "\$info[4]  = ", sprintf ("
+%6d", $info[4]), "\tcurrent attribute used for Write\n";
                        print "\$info[6]  = ", sprintf ("%6d", $info[5
+]), "\tX of the starting point of the current console window\n";
                        print $fh_log_file "\$info[6]  = ", sprintf ("
+%6d", $info[5]), "\tX of the starting point of the current console wi
+ndow\n";
                        print "\$info[6]  = ", sprintf ("%6d", $info[6
+]), "\tY of the starting point of the current console window\n";
                        print $fh_log_file "\$info[6]  = ", sprintf ("
+%6d", $info[6]), "\tY of the starting point of the current console wi
+ndow\n";
                        print "\$info[7]  = ", sprintf ("%6d", $info[7
+]), "\tX of the final point of the current console window\n";
                        print $fh_log_file "\$info[7]  = ", sprintf ("
+%6d", $info[7]), "\tX of the final point of the current console windo
+w\n";
                        print "\$info[8]  = ", sprintf ("%6d", $info[8
+]), "\tY of the final point of the current console window\n";
                        print $fh_log_file "\$info[8]  = ", sprintf ("
+%6d", $info[8]), "\tY of the final point of the current console windo
+w\n";
                        print "\$info[9]  = ", sprintf ("%6d", $info[9
+]), "\tmaximum number of columns for the console window\n";
                        print $fh_log_file "\$info[9]  = ", sprintf ("
+%6d", $info[9]), "\tmaximum number of columns for the console window\
+n";
                        print "\$info[10] = ", sprintf ("%6d", $info[1
+0]), "\tmaximum number of rows for the console window\n";
                        print $fh_log_file "\$info[10] = ", sprintf ("
+%6d", $info[10]), "\tmaximum number of rows for the console window\n"
+;

                        print "\n";
                        print $fh_log_file "\n";
                    }

                else

                    {
                        print "undefined event type.\n";
                        print $fh_log_file "undefined event type.\n";
                    }

                print "\n";
                print $fh_log_file "\n";
            }

        sleep 0.01;
    }

print "The time to stop listening has been reached.  Program is ending
+.\n\n";
print $fh_log_file "The time to stop listening has been reached.  Prog
+ram is ending.\n\n";
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