I think it all depends on what you are comparing this phone to. My previous phone came out awhile ago, so of course the HTC One feels very smooth for me.
For me, the smoothest rom is vanilla Android, namely GPE. AOSP roms (like CM) seem to stutter when scrolling, such as in the Settings menu.
If you are comparing Android to iOS, however, there was a post a couple of years ago stating that it is because of how Android renders the interface that makes it laggier than iOS. This is not the post itself, but it breaks it down: http://www.redmondpie.com/heres-why-...ndows-phone-7/
in my opinion,
Facebook or 3rd party integration is the problem; un-link facebook account or at least use your phone without internet connection (3G or wifi i mean) for testing.
i am a one user, with stock 4.3 and happy with it
As this is not directly related to the HTC One and has become a bit of a phone comparison thread, this is classed as an OT thread and has been clsoed. Please see the link in my signature for OT section in XDA. This would be a better place for threads of this type.
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