Indexed Array of Objects taking long time while doing $match

[Merlin_Baptista_B]

I am having the data like below…

{
  "a" : 
  [
    {
	 "b" : 
	 [
		{
		  "c" : 10
		}
	 ]
    }
  ]
}

And Created an index as a.b.c
When i am trying to do $match : {“a.b.c” : “10”}… It takes long… especially

Any suggestions…