The storage of data is in computer memory instead of on disk or other external storage devices. This allows for faster access to the data, which is particularly useful for processing large amounts of data quickly and enables real-time data analysis and reporting. By storing data in memory, TM1 can perform calculations and generate reports much faster than traditional databases.

Write-back capability, a feature of cell-oriented databases, enables users to update and save changes made directly to cells in the database, rather than exporting and importing data for editing. In a cell-oriented database, data is stored and processed at the level of individual cells, rather than in pre-defined structures such as tables or columns.

TM1 optimizes calculations by performing them only on data that has actual values or changes, instead of recalculating everything in the cube. It saves time by reducing the amount of data processed during calculations and identifying only the cells that need to be recalculated based on updated or modified data.