As I mentioned before, I wanted to try to apply the macroblock selection approach from VP7 encoder in VP6 encoder. Well, it was easy to implement: instead of preparing all macroblock modes and then trying which is the best one now it tries macroblock modes (starting with inter mode now) and stops when the result is good enough. In this mode encoding seems to go couple percent faster and the resulting size at the same quantiser can differ somewhat in both directions. You can try it yourself by using fast
encoder option.
The encoder is still a failure though.