Optimizing for exact array matching over MongoDB collection

Question

I have a collection where I only ever need to look up documents by whole arrays; I can’t think of any scenario where I’d want to look up documents by just one value of that array. Unfortunately, the multikey feature that is always activated for array values apparently can’t be deactivated.

In the documentation it says “The index will be used to lookup a subset of the values (currently the first one) and then the document will be inspected for the exact match.” I think this greatly decreases the performance in my case. Despite the index some lookups take 70 ms and some several minutes, because, depending on the first element, MongoDB sometimes has to search through a few thousand or several hundred thousand documents. At least that is my theory.

Is there some way to avoid this problem, or should I rather serialize my arrays and store them as strings?

Thanks in advance!