Post Indexer Brings Sites Down When Cron Runs

Hello,

We use a the Jetpack monitoring service on many of our subsites on a WP 4.0 Multisite Network and sine April 2014 we have been receiving site down notices very frequently.

Over the months I have disabled various plugins and all backup solutions, etc. for days at a time trying to identify the source of the cyclic server overload without success.

However today, it appears the downtimes may be related to when the Post Index cron job runs.

What other WPMUDEV plugins have a dependency on Post Inder?

If I disable Post Indexer for 24 to 48 hours to see if the downtimes cease occurring, will the dependent plugin functions cease to work or will they continue to work but use the index info that exists right before indexer is deactivate?

Please advise your recommendations.

Thanks,
Phil D