There is a setting in the group policy for the computer, so you don't have to manually edit the registry.
- Open run dialog: Win+R
- Type "gpedit.msc" and select OK
- Browse to Computer Configuration\Administrative Templates\Windows Components\Search
- Select "Disable indexer backoff", and set it to Enabled.
This setting will not take effect until the service is restarted. The easiest way is to just reboot your computer, but you can do it live
- Open run dialog: Win+R
- Type "services.msc" and select OK
- Scroll to "Windows Search"
- Right click and select "Restart"