My first thought since you mentioned slower in coin and other unranked rounds was probably due to apparel attribute, but I just checked all the available attributes and none of them (at least on the apparel I have) offer Slower 3wd Swing Meter, so that theory seems unlikely.
I have Slower Driver, Hybrid, Irons, Wedges available but nothing for meter speed on 3wd or putter.
That's all I have.