Description:
------------
seeing 10-100x slower processing of non-fatal errors using custom error handler function on 7.4.7-7.4.8 vs. 7.4.0-7.4.6.

https://3v4l.org/WcFJK/perf#output

not a c programmer, but i wonder if it could be caused by the following 7.4.6 bug fix:

https://bugs.php.net/bug.php?id=79599

Test script:
---------------
<?php

// see https://3v4l.org/WcFJK/perf#output

// 2020.07.25

// performance hit processing non-fatal errors w/ custom error handler (e_notice, e_warning)
// affects versions 7.4.7 & 7.4.8

// array of seq. ints
$start = 3;
$number_of_values = 5000;
$seq_array = range($start, $start+$number_of_values-1);

// set error handler
function error_handler_fn($errno, $errstr, $errfile, $errline) {
    $dummy = '0';
    // print_r(implode(", ", Array($errno, $errstr, $errfile, $errline))."\n");
}
set_error_handler("error_handler_fn");

// array to index
$array = Array(1,2,3);

// run loop
$t1 = microtime(true);
foreach ($seq_array as $val) {

	$nothing = $array[$val]; // E_NOTICE (8) - try to index array at undefined index (performance issue)
	
	// $nothing2 = count(); // E_WARNING (2) - try to count nothing (similar performance issue)

}
$t2 = microtime(true);
$outmsg = "\n\nRun time: " . round(($t2-$t1)*1000.,2) . " milliseconds (" . phpversion() . ")";
print_r($outmsg);

?>

Expected result:
----------------
execution time comparable to 7.4.6 and earlier

Actual result:
--------------
execution time 10-100x longer on 7.4.7-7.4.8 than on 7.4.6 and earlier