There alerady exists an explanation of how to reduce this, here are the crucial steps:
- Open a Sharepoint Management Shell
- Set-SPEnterpriseSearchService -PerformanceLevel Reduced
- Get-SPEnterpriseSearchService
Should show "Performance Level: Reduced" now - Open C:\Program Files\Microsoft Office Servers\15.0\Search\Runtime\1.0\noderunner.exe.config in Notepad
- Update <nodeRunnerSettings memoryLimitMegabytes=”0″ /> to say 100
- Restart SharePoint Search Host Controller Service
And you are done.