Hi Dijana,
Here are some links to check out:
https://securosis.com/assets/library/reports/BestPracticesforEndpointDLP.pdf
https://support.symantec.com/en_US/article.TECH220293.html
https://support.symantec.com/en_US/article.TECH247513.html
https://www.symantec.com/connect/forums/dlp-endpoint-performance-improvements
https://www.symantec.com/connect/forums/network-discover-scan-and-max-file-size
Thanks!