I did a performance check, and I saw, if you push more than one value it can be faster the array push, that the normal $array[] version.
Case 1: $array[] = something;
Case 2: array_push[$array, $value];
Case 3: array_push[$array, $value1, $value2, $value3 [...]]; $values are definied
Case 4: array_push[$array, $value1, $value2, $value3 [...]]; $values are definied, when $array is not empty
Case 5: Case1 + Case 3
Case 6: Result array contains some value [Case 4]
Case 7: Result array contains same value as the push array [Case 4]
-----------------------------------------------------------------------------------------------------------
~~~~~~~~~~~~ Case 1 ~~~~~~~~~~~~
Times: 0.0310 0.0300 0.0290 0.0340 0.0400 0.0440 0.0480 0.0550 0.0570 0.0570
Min: 0.0290
Max: 0.0570
Avg: 0.0425
~~~~~~~~~~~~ Case 2 ~~~~~~~~~~~~
Times: 0.3890 0.3850 0.3770 0.4110 0.4020 0.3980 0.4020 0.4060 0.4130 0.4200
Min: 0.3770
Max: 0.4200
Avg: 0.4003
~~~~~~~~~~~~ Case 3 ~~~~~~~~~~~~
Times: 0.0200 0.0220 0.0240 0.0340 0.0360 0.0410 0.0460 0.0500 0.0520 0.0520
Min: 0.0200
Max: 0.0520
Avg: 0.0377
~~~~~~~~~~~~ Case 4 ~~~~~~~~~~~~
Times: 0.0200 0.0250 0.0230 0.0260 0.0330 0.0390 0.0460 0.0510 0.0520 0.0520
Min: 0.0200
Max: 0.0520
Avg: 0.0367
~~~~~~~~~~~~ Case 5 ~~~~~~~~~~~~
Times: 0.0260 0.0250 0.0370 0.0360 0.0390 0.0440 0.0510 0.0520 0.0530 0.0560
Min: 0.0250
Max: 0.0560
Avg: 0.0419
~~~~~~~~~~~~ Case 6 ~~~~~~~~~~~~
Times: 0.0340 0.0280 0.0370 0.0410 0.0450 0.0480 0.0560 0.0580 0.0580 0.0570
Min: 0.0280
Max: 0.0580
Avg: 0.0462
~~~~~~~~~~~~ Case 7 ~~~~~~~~~~~~
Times: 0.0290 0.0270 0.0350 0.0410 0.0430 0.0470 0.0540 0.0540 0.0550 0.0550
Min: 0.0270
Max: 0.0550
Avg: 0.044
Tester code:
// Case 1
$startTime = microtime[true];
$array = array[];
for [$x = 1; $x