I think I am seeing some improvement after disabling HTC Motion Launch and Attentive Phone. ( Along time ago I had a Samsung Phone that was trying to do too much fancy stuff in the background and disabling the Motion Stuff helped)
Also, I seem to have gotten some improvement out of removing and reinstalling some apps. It seems like the big Live Tile Apps were an issue like Weather & MSN Money.
See the article excerpt below for a brief description of the stuttering behavior, when compared to the M8's Android Twin.
HTC One M8 for Windows review | The Verge
Though the M8 for Windows has the same processor and RAM as the Android model (it’s a 2.3GHz quad-core Qualcomm Snapdragon 801, for those interested), it doesn’t perform as smoothly or as quickly as its Android counterpart. Everything feels a little slower on the Windows version for some reason, with animations that stutter and hesitate. It’s a bit out of character for the M8, which is a very fast and responsive Android phone, and for Windows Phone in general, which is usually snappy and responsive on even the most basic hardware. Perhaps HTC has some tuning to do to make Windows run better on the M8’s hardware.