What's the Best Way to Secure an SMB Server Without Sacrificing Performance? or Why Is My SMB Server

If your SMB server is crawling, try disabling SMB signing if you’re on a trusted network. It adds overhead.

Also, check for NIC offloading settings. Sometimes disabling RSS or LRO can help weird latency issues.

And +1 to everyone saying ditch SMBv1. It’s slow *and* unsafe. SMBv3 with encryption is the way.