As i couldnt get any satisfying answer to my Question it seems we have to write our own program for that, we are in the design phase and we are thinking which format shall w
I use an excellent program called OmegaSync for my backups, but it will only handle Informix via ODBC and not directly. If you find you can use OmegaSync, you'll find its performance to be excellent, because it compares the databases first, and then syncs only the differences. You might want to use this idea if you decide to do the programming yourself if efficiency is your number one goal.
But programming database conversion is very complex as others answers to your question have said. So why not just develop the SQL you need, and do the conversion that way. For example see: Convert Informix Schema to Oracle Schema Or Any Other RDBMS For moving the data, check out sources like: Moving non-informaix data between computers and dbspaces
You can optimize the SQL to what I'm sure will be an adequate speed if you dump and load your data smartly.