Query takes longer as domain user than local admin
After a few hours and some pow-wow time with my developers, we discovered the issue: 

I typically uncheck login\logoff auditing in SQL profiler, but it happened to be the window I needed to peek on the cause. When running 'as admin' the application connects using TCP\IP. 

When running as just a user, the app connects over Named Pipes. I'll still need to work out why, but in the mean time I can force the app to run in TCP\IP using a different connection string.