Heimdal is an implementation of Kerberos 5 that aims to be protocol compatible with existing implementations and RFC 4120. It supports Kerberos V5 over GSS-API (RFC 1964) and PK-INIT (smartcard support) for Kerberos, and includes a number of important and useful applications (rsh, telnet, popper, etc.). Heimdal also contains an ASN.1 compiler, X.509 library, and NTLM (v1 and v2) library.
The problems found in arla 0.28 is fixed in 0.29. The speed problem is probably related to the verbose logging.