I have a stand-alone MongoDB instance running in windows. It's recently experiencing slowness and my troubleshooting has found the following symptoms:

1. The slowness normally occurs after a full text search query against a huge collection. I guess this is because it swaps many pages in the collection from disk into memory hence data from other collections are squeezed out of memory.

2. The server memory usage is capped around 55%. The server (Win2012) has 32GB of memory but MongoDB is not trying to utilize beyond 16GB.

I have seen a couple of Q&A in limiting MongoDB memory usage but not on how to encourage MongoDB to be more greedy.

MongoDB: 3.2.0
Storage Engine: wiredTiger
OS: Win2012
Memory: 32GB