Elastic Search high CPU Usage with More Like This query

Clash Royale CLAN TAG#URR8PPPElastic Search high CPU Usage with More Like This query
We tried using a more_like_this query in ES on a text field with 500-1500 words in each post and about 500,000 posts. The CPU usage was very high (almost 100%), but it looks like JVM Memory Pressure was normal.
more_like_this
One optimization that I think will help is adding/saving term_vectors. Will that help with CPU utilization? Trying to understand why this happened in the first place.
term_vectors
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