Perhaps you know this and are already using this latest firmware, because it seems to be released a while back (Dec 19).
Anyway, have a look here ...

RICOH IMAGING COMPANY, LTD. wishes to announce the release of Firmware Update Software Version 1.01 for PENTAX K-3.

Changes to V1.01
  • Shorten processing time of combining time for HDR Capture.
  • Improved performance of continuous shooting when using phase-matching autofocus.
  • Extended enlarged display time for live view.
  • Improved stability for general performance.