Assuming that's the output of 'vmstat 1' and not some other delay, 50MB/second of sustained writes is usually considered 'a lot'.I don't have iostat on that machine, but vmstat shows a lot of writes to the drives, and the runnable processes are more than 1:
6 1 0 3617652 292936 2791928 0 0 0 52430 1347 4681 25
19 20 37
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