LoadRunner provides the C scripting functions lr_encrypt and lr_decrypt to provide additional security.
The use of these functions will not impose any negative impacts during the load testing (should not decrease performance nor add overhead).
Loadrunner provides a feature to display an encrypted password in the script. This encrypted password is decrypted by the LoadRunner runtime component before the request is sent out on the wire.
If, while recording, Loadrunner sees an encrypted password on the wire -- it will record an encrypted password string in the script. If the client sends password as plain text, LoadRunner records plain text in the script. You have the option of encrypting it by highlighting the password string, right click, and choose "Replace with encrypted string".