The post shows a 3.5x performance improvement for requested 4-way parallelism, so that&#x27;s a significant improvement right now!<p>You might be surprised how many queries are bound by memory bus bandwidth and CPU, rather than I&#x2F;O ... but even I&#x2F;O bound queries may benefit:<p>Remember that postgres is a &quot;demand-pull&quot; system. A sequential scan node returns a single tuple at a time, whenever its parent node asks for a tuple. So there can be considerable time between requests for an actual disk block.<p>Parallelizing the scan should result in more frequent requests to the disk controller, which could then have better opportunity to optimize reads - even for a single disk. Since most of the latency for spinning disks is seek time, having more outstanding block-read requests should help performance.