E.g. If there are two processes, A, the writer, and B the reader. Both are in wal mode, sync=normal. If process A writes a large amount of data, and the OS has not fsync'd that to disk yet, are those writes now in the RAM of the OS buffers? Will process B's reads now be faster as some of the data is still in the RAM backed OS buffers which should be faster to read than the disk based data? How much faster would it be? Would it be Redis-like speeds for simple lookups?