Disclosed herein are exemplary embodiments of innovations in the area of encoding pictures or portions of pictures and determining whether and how certain encoding operations should be performed and flagged for performance by the decoder in the bitstream. In particular examples, various implementations for selectively encoding picture portions (e.g., blocks) in a skip mode (e.g., as in the skip mode of the H.265/HEVC standard) are disclosed. Embodiments of the disclosed techniques can be used to improve encoder efficiency, decrease overall encoder resource usage, and/or improve encoder speed. Such embodiments can be used in encoder modes in which efficient, fast encoder performance is desired (e.g., during encoding of live events, such as video conferencing).