Hacker News Reader

For a lot of array-heavy applications (where you store all kinds of data in giant multi-level PHP arrays), the memory usage alone counts for most of the speedup; instead of wading through tens or hundreds of MB of array structures, PHP 7 trimmed things down by a factor of 2 or more.

There are a lot of PHP apps/CMSes/etc that gained 30-50% speedups due to just that improvement. Other more optimized apps/scripts saw a much more modest gain.

View on HN

IIRC, a PHP array entry had 127 bytes of overhead. PHP 7, that went down to 42(?). Also, IIRC, for JVM, it's .. 37? 40? PHP7 got array overhead down a lot, and I do believe that's where a lot of speed improvement came from (though certainly not all of it).

PHP array is equivalent to LinkedHashMap and yes, it has 40 bytes overhead per entry in Java.

This talk's slides have a good summary of how much overhead was reduced: http://www.slideshare.net/nikita_ppv/php-7-what-changed-inte...

Reply on news.ycombinator.com