[PrestaShop 1.6.1.23] Cannot add a new shop in multistore

[ferdis]

Hello,

when I try to add a second shop to multistore, or update the existing one, I'm waiting about 3 minutes until the allocated script memory is exhausted and the script finally crashes with the message:

Fatal error: Out of memory (allocated 2862275072) (tried to allocate 20480 bytes) in /classes/db/DbPDO.php on line 154

I allocated 3 GB of memory for the script, but it's not enough. The profiler is unusable in this case. The shop is running on PrestaShop 1.6.1.23, counts around 1000 simple products. I tried PHP5.6, PHP7.0, PHP7.2, all with the same result.

All files and folder permissions are 777 and with the right owner.

I already set up successfully recently a multistore on other server (older version of 1.6), with more products and far less memory (<512MB).

Does someone have a hint, what to do?

Thanks.

[ferdis]

I turned off all 3rd party modules and cleared unneeded records from db via MyPresta's Prestashop Database Optimization module, but the issue still remains.