I watch a lot of media with subtitles, and there appears to be a short spike in cpu/gpu usage when subtitles are rendered in kodi krypton, resulting in single or multiple frame drops. I finally found a file where this frame drop is easily visible, especially with the default mixed chinese/english subtitle track:
File-Upload.net - SubtitlesFrameDropTest.mkv
It is very pronounced with 8.0.1f, but the effect has been visible with the older krypton versions as well. On LE Jarvis, it is fine (just tested it again).
[Edit: S905X shows same behaviour, but for whatever reason cannot play this test file. I will try to find another easily visible example. Until then removed the S905X tag]