Symptoms

SmartForm doesn't load for 3 users and server CPU is at 99% due to LSASS.exe
 

Diagnoses

Please help us troubleshoot why 3 users cannot open a smartform and why the local security authority process would be using almost 50% CPU.

When a SmartForm loaded and it was attempting to resolve logged in users, it accessed the LSASS.exe server sub-system and caused the CPU to reach 99%. An IIS reset temporarily resolved the issue.
 

Resolution

Microsoft found the server was trying to resolve to a domain which was closed by a firewall. The firewall was opened... and no more issues.