I'm having the same hiccups since updating to 4.4 (4.3.17 practically) but it could be a "nocebo" effect due to the hefty amount (45GB) of titles, box art and videos (unrelated to the RCA topic I made previously).
I'm pretty sure though that things were slightly faster before (3B with 4.3 instead of 3B+ with 4.4) and that "hang for 5 seconds" thing I'm too having didn't happen until 4.3.16/17. To put it in a sentence, navigation feels a bit more laggy and stiff than before.
However, I'm not having the second part of adm166's problem with images showing grey, etc which sounds like a VRAM issue.