Optimize transaction past cone check (iotaledger#1153)

* WIP debugging of markers and heavy Tangle walking issue

* Clean up debug prints

packages/tangle/utils.go

@@ -122,6 +122,7 @@ func (u *Utils) TransactionApprovedByMessage(transactionID ledgerstate.Transacti
 			continue
 		}
 
+		bookedParents := make(MessageIDs, 0)
 		u.tangle.Storage.Message(messageID).Consume(func(message *Message) {
 			for _, parentID := range message.StrongParents() {
 				var parentBooked bool
@@ -132,13 +133,26 @@ func (u *Utils) TransactionApprovedByMessage(transactionID ledgerstate.Transacti
 					continue
 				}
 
-				if u.MessageApprovedBy(attachmentMessageID, parentID) {
+				// First check all of the parents to avoid unnecessary checks and possible walking.
+				if attachmentMessageID == parentID {
 					approved = true
 					return
 				}
+
+				bookedParents = append(bookedParents, parentID)
 			}
 		})
+		if approved {
+			return
+		}
 
+		// Only now check all parents.
+		for _, bookedParent := range bookedParents {
+			if u.MessageApprovedBy(attachmentMessageID, bookedParent) {
+				approved = true
+				return
+			}
+		}
 		if approved {
 			return
 		}