APT_BUFFER_DISK_WRITE_INCREMENT

APT_BUFFER_DISK_WRITE_INCREMENT sets the size, in bytes, of blocks of data being moved to or from disk by the buffering operator.

The default is 1048576 (1 MB). Adjusting this value trades amount of disk access against throughput for small amounts of data. Increasing the block size reduces disk access, but might decrease performance when data is being read/written in smaller units. Decreasing the block size increases throughput, but might increase the amount of disk access.