Hi stiegi,
You're confused about the throttle option. It has nothing to do with input lag. The -throttle option MUST be enabled for the -syncrefresh option to work. This is true for GroovyMAME and any MAME compiled with the patch I posted in Eiusdemmodi.
The only reason to disable -throttle is to allow smooth scrolling in combination with -triplebuffer when you're running an official build of MAME since version v0.114.
Basically if you're running GM just leave the default options.