Thanks, I've read the article.

Unfortunatelly it is irrelevant to my question, because I asked specifically about FB Classic and tests were conducted on Superserver.

Moreover it was version 2.5.1. As I read earlier there were some problems with 32 bit version 2.5.1 on machines with more than 4GB RAM. I don't know if this was true or not in this particular case.

I saw the comparision table, author of the article forgot to mention that 64 bit version uses 10-15% more memory than 32 bit when executing queries.

BTW: What do you mean by the "real field"?

Thanks for the valuable input!