Fixed. It's yet another effect of the complete rewrite of how ADOM works internally (e.g. exchanging the REPL with an event system). This still needs some experimenting as there are many ways to use the new event system.
To explain this:
In the new system events connected to a specific point in time are posted to an internal event queue. One such event might be "let the player move".
Whenever this event gets called, the energy of the player is increased by his speed and as soon as he has accumulated 1000 energy points he can act.
As a result of the action is energy will be decreased (by 1000, that being the default value, but e.g. moving with 7LB just deducts 750 energy points, etc.)
Currently the event gets executed every 100 internal time units (this being equal to the speed value, assuming that after 10 executions on average you will have accumulated the required 1000 energy points). For monsters this works the same.
If you e.g. have a speed of 200, only 500 time units will pass (as very 100 time units your energy gets increased by your speed of 200).
Now one could go to smaller time units (e.g. of 10) increasing energy by one-tenth of the current speed - but this already raised questions about the remainder values (e.g. the 4 in speed 124).
Now one also could say that instead of executing every 100 time units, ADOM could execute it in INTEGER(1000 / current speed) * 100 time units and then act every time. But this would prevent intermediate effects (if there e.g. were a quickening wizard casting slowing magic on you or whatever).
So the overall system is quite complicate and having changed code of ADOM that is among the oldest stuff in the game sadly has some side effects. It's for a reason that sometimes development is tough ;-)
But long talk, short answer: for now this specific problem should be fixed.