This is really just a post for me to keep track of sites that have got or had performance issues with FreeRADIUS when authenticating to Active Directory via ntlm_auth and Samba.
The issue crops up on the FreeRADIUS mailing list with an increasing frequency, so trying to collate posts to keep track of what people have tried as a solution.
Note the vast majority of sites are universities. I believe this is because there is a unique problem that does not occur in business: once an hour, many students and staff all walk around the site at the same time, authenticating to different wireless access points. This causes massive increase in concurrent authentications.
Some of my posts on the issue: