Low latency data storage and retrieval

I have a data model whereby I have a finite number of rows and defined columns of data - think of a standard, single database table. In the past, I've used JavaBeans to store data values. I want to move to a model with improved speed and lower latency. I've been considering a number of basic Java structures for this, but can't seem to figure out which one is most suitable.

The application will simply receive data from several threads and update the values of specific data items in the storage mechanism based on a defined set of rules. So, if I receive a data update for a data item, I need to iterate through the data structure, find the correct row, update the data (column values) and move on to the next data update.

Does anyone have any thoughts for the optimum design approach? I think that using the Bean approach is too hefty, but, it's only a gut feeling and I'd like to test some other approaches.