ok, I have some very general question. Is anybody aware about how Netsuite decieds which datacenter to use for a new client? All our clients are in Europe but I see that some environments are placed in North America datacentre and that doesn't looks as logical decision. One of such enviroment has huge issue with slowness (at server side, not scripts or wf) so I wonder if datacenter location could have impact on that?

very likely. For EU clients, I am surprised that did the NA datacenter because of GDPR concerns.

Not sure if this is helpful, but usually it’s based on the HQ/office location you provide them when initially signing up and sometimes the work location of the person who signs the contract with NetSuite. E.g. one company I worked for whose official HQ was in California but 95% of its employees and operations were in Washington DC got setup on US West versus US East. And of course once it’s set it can be risky/expensive/annoying to change data centers so companies rarely bother to change.