Cache Chunks is an option that tells NewsBin to save chunks in memory instead of writing each chunk to disk. This option increases memory usage by 80MB to 100MB but, cuts disk I/O in half, which is more of a bottleneck.
The option is selected under Options/Advanced under "Spooler Settings" with the "Cache Chunks" option.
When this is enabled, NewsBin stores up to 100 chunks in memory. When all chunks are available to assemble a file, they are assembled directly from memory into the resulting file. If there are more than 100 chunks, the older chunks are written from the cache to disk in the Chunks folder and the new chunks get stored in the Chunk Cache. When you exit NewsBin, any chunks in the Chunk Cache are written to disk.
NOTE: This functionality was removed after version 5.52.