it appears the write queue performs just as good at 10 MB as 50 MB

src/session.cpp

@@ -234,7 +234,7 @@ namespace libtorrent
 
 		// the max number of bytes pending write before we throttle
 		// download rate
-		set.max_queued_disk_bytes = 50 * 1024 * 1024;
+		set.max_queued_disk_bytes = 10 * 1024 * 1024;
 		// flush write cache in a way to minimize the amount we need to
 		// read back once we want to hash-check the piece. i.e. try to
 		// flush all blocks in-order