PHP Memory Limit
PHP “Memory Limit” usually defined on your php.ini (the default configuration) file, is the Total PHP Server Memory. Do not confuse with hardware physical memory, which usually takes the form of cards (DIMMs) attached onto the motherboard. Our plugin can show you your hardware memory (look the Hardware Memory Tab).
The PHP memory limit needs be bigger than WordPress Memory Limit and not bigger than your Hardware Memory.
This sets the maximum amount of memory in bytes that a script is allowed to allocate. This helps prevent poorly written scripts or any temporary fail for eating up all available memory on a server…
We suggest 512Mb.
You can use our Premium Version plugin to increase that to up to 1024 Mb without make changes in your php.ini file and and risking accidental file alterations.
To know more about your php.ini file and your total server RAM hardware memory, talk with your hosting company.