Brightness/Volume buttons slower

[orfeas0]

Does anyone else have this issue since upgrading to Yosemite or just me?
Controlling the brightness and/or volume by pressing the equivalent keys (i.e. f5,f6,f11,f12) isn't instant like it used to be in Mavericks and before that.

 

[Mac210882]

On startup they're as responsive as ever, but as time goes on (i.e. two or three hours of working) I'm getting more and more lag on the brightness/volume controls to the point at which they just stop responding.

This is on a 2014 rMBP (i7/16GB/1TB SSD) connected to 2 x Thunderbolt displays

Very annoying