update the ghost sparingly

src/net/torvald/terrarum/modulebasegame/gameitems/FixtureItemBase.kt

@@ -67,6 +67,8 @@ open class FixtureItemBase(originalID: ItemID, val fixtureClassName: String) : G
         }
 
 
+        // update the ghost sparingly
+        if (INGAME.WORLD_UPDATE_TIMER % 2 == 0) {
             (INGAME as TerrarumIngame).blockMarkingActor.let {
                 val item = ghostItem.get()
 
@@ -84,6 +86,7 @@ open class FixtureItemBase(originalID: ItemID, val fixtureClassName: String) : G
                 }
             }
         }
+    }
 
     override fun effectOnUnequip(actor: ActorWithBody, delta: Float) {
 //        ghostInit = false