Speed up your SharePoint 2013 server

Reduce the CPU impact the search service:

PowerShell: Set-SPEnterpriseSearchService -PerformanceLevel Reduced

Reduce the memory usage by noderunner.exe processes:

1.       Open file in notepad:  C:\Program Files\Microsoft Office Servers\15.0\Search\Runtime\1.0\noderunner.exe.config

2.       Change the value at <nodeRunnerSettings memoryLimitMegabytes="0" /> to 100 (Megabytes) for example.