Shimano 105 shifting force. Can it be reduced?

[rusty bearing]

Strangely we had a bike in the workshop today exhibiting the same problem, real pressure needed to change front gears. Close inspection revealed that the cable was incorrectly clamped behind the small tab on the mech instead of running over it and then behind the washer and into the horizontal groove where it was supposed to sit. Correctly fitted the pressure needed to change gear was back to normal. Difference was only 0.125 from the pivot but a big difference to the shift action
May not be the answer here but worth checking.

 

[slowmotion]

rusty bearing, I thank you for that post, even though it will probably cause me an entirely sleepless night