To my knowledge INDEXED_EXTRACTIONS only works on csv, psv, JSON, or xml data. It causes the KvP to be indexed which takes up more disk space but can provide a boost in speed at search time. If you're not indexing those types of data however, the setting won't do anything.
If you do desire to fully index the field however and you're not ingesting such structured data, you can do so with the TRANSFORM-className stanza in props.conf and a corresponding entry in transforms.conf.
Doing so however would add more "pressure" on the indexing side as it takes longer to write more data and this is probably not the solution you're looking for since you're describing the data as "heavy". If you're looking for extra bandwidth on the indexing side, let us know and we can offer some solutions. If you're experiencing slow search across this data, then we can offer other ideas.
Thanks. The AD feed is pretty busy, and I have a customer who wants to present a dashboard that does about 9 or 10 different panels, with different counts of fields and values. Unfortunately, the dashboard takes waaay to long, so I'm looking for ways to speed it up.