Cassandra 1.0 introduces several improvements to its storage engine, enhancing memory and disk management for better performance. Key updates include the addition of an off-heap row cache for reduced JVM heap requirements, self-tuning memtable sizes for optimal balance between write speed, compaction overhead, and memory use, a global commitlog_total_space_in_mb setting to manage data replay on startup, and explicit reference counting for efficient obsolete data file cleanup post-compaction. These enhancements address common pain points for Cassandra administration and improve overall performance.