Click your policy for client computers and select Edit.
Click Settings, click Detection Engine → Exclusions, and then click Edit next to Performance exclusions.
Click Add, type the directory that you want to exclude from scanning into the Path field, and add a comment for the exclusion in the Comment field. Click OK. Make sure the file path for your exclusion is in the correct format, for example, "C:\Users\[username]\Documents\file.exe".
Do not use wildcards for directories!
Wildcards for directories in paths are not supported. Read more about exclusions and wildcards here.
Click Save when you are finished adding exclusions.