So, quick update on this, i turned off all outputs, and turned of debug option and managed to do the entire 3 million records in one go without running out of memory for the full run.
Secondly, when running this previously I was keeping an eye on my digital ocean CPU, Load, Memory graphs to see how hard the server was being hit, and it was jumping from 4% CPU usage to 90% when the script ran, however for the full run with Debug off, it never went over 15% CPU usage, which I found very interesting.
Here are some stats over 24 hours of my Application Container, the 100% is before turning off Debug and the right hand side is after turning it off, considering the server action never changed at all.
This is the database container, with 50% CPU going down to 10%
I am kind of wondering if, in light of this, it might be a good feature request to see if Wappler could give a debug on/off swith on a per server action basis.