Best way to loop over mongo collection?

I have a mongo collection in Rails where I use it this manner:

collection.find(selector, options).to_a

I have around 47K rows of data, and it seems very slow doing it this
way.

Should I be using the cursor instead of converting to an array? If so,
can anyone point me to the usage pattern? Or, is using to_a fine? Just
wondering if converting to an array is too slow.

How about you tell us what ODM you are using?

Jordon Bedwell wrote in post #1099153: