MongoDB sort is extremely slow even on indexed fields

So I had this issue today where my MongoDB queries where extremely slow and timing out. I posted this question - MongoDB too many records? and his suggestion was right wherein I had to ensureIndex and remove case-insensitivity. I tried it in Mongo shell, it worked perfectly.

However, when I ran it via PHP, it was still the same :( I then realized the query had a sort on "id" (not _id) field and when I removed that, things were blazing fast. But with the sort, it was REALLY slow. I already had an index on the id field. This is the query btw :

db.tweet_data.find({ 
...     $or: 
...         [ 
...             { in_reply_to_screen_name: /^kunalnayyar$/, handle: /^kaleycuoco$/, id: { $gt: 0 } }, 
...             { in_reply_to_screen_name: /^kaleycuoco$/, handle: /^kunalnayyar$/, id: { $gt: 0 } } 
...         ], 
...     in_reply_to_status_id_str: { $ne: null } 
...     
...     } ).sort({id:-1})explain()

So my indexes are : (not composite) { {id:-1} , {handle:1}, {in_reply_to_screen_name:1} } After some reading I realized it should have been a composite index and I tried two variations to no success : 1. {handle:1, in_reply_to_screen_name:1, id:-1} 2. {id:-1,handle:1, in_reply_to_screen_name:1}

I am not sure where I am going wrong, but I am pretty sure the issue is indexing here. I am just too buzzed and can't understand the order and the fields to index