Complex sentence: LevelDB also excels at batch writes, but is slower than SQLite when dealing with large values, and the benchmark artificially degraded SQLite performance by indexing the key twice and not using write-ahead logging.
Split into simpler sentences: LevelDB also excels at batch writes, but is slower than SQLite when dealing with large values. However the benchmark was found to artificially degraded SQLite performance by indexing the key twice and not using write-ahead logging.