Exteris,

Вроде бы DiXML https://www.yunqa.de/delphi/products/xml/index умеет работать с огромными файлами

https://www.yunqa.de/delphi/wiki/xml/index Q: Can DIXml read in very large XML files? I have files that are over 900+ MB - that other components cannot parse due to their size. They give Out of Memory errors.

A: Yes, DIXml can parse XML files of virtually any size with no memory constraints. This is true of the SAX, SAX2, and XmlReader interfaces. The XmlReader interface is recommended because it is more flexible and user friendly. Be careful, however, if you build a DOM tree: This will cause DIXml to load the entire document into memory and may result in memory errors if it exceeds the available RAM. On the other hand, DOM is only needed for XML tree manipulation. For just parsing and extracting data, the XmlReader is much faster and uses a minimum of resources only, including memory.

тогда уж лучше с Firebird