Hi Brandon,
In your case, I would suggest trying the Index Table engine:
– Index table overview
– Configuring & Generating
– Enabling the index
I strongly believe that in your case it would be beneficial, as all keywords would be organized by occurences to a single table, thus giving much much better performance overall, while using only the fraction of the resources.
The index table engine calculates the relevance by keyword occurences, which is not possible otherwise. You can change field priorities on this panel, if you prefer some fields over others.
I hope this helps!