Seeing decent FPS at LAX using DX10 fixer but having real stuttering problems.
Do you imply with this that you don't get any stutters without the DX10 fixer ? Note, an easy way to test might be trying under DX9, so you won't have to change anything in the configuration of the fixer.
Note that, KLAX is DESIGNED to work with DX10 and doesn't require any fixer, but I cannot possibly say what the fixer does to fix issues with add-ons that don't work in DX10, that might affect addons that DO.
But first, try in DX9, if the stutters are still there, the reason might be entirely different.