A customer has a multisite cluster (two sites, each site in its own data center) and users experiencing a slow response when searches are run on search heads located in either site. The Search Job Inspector shows the delay is being caused by search heads on either site waiting for results to be returned by indexers on the opposing site. The network team has confirmed that there is limited bandwidth available between the two data centers, which are in different geographic locations.

Which of the following would be the least expensive and easiest way to improve search performance?