So this is something that needs to be more precisely defined. But
when starting a reasoner, it is not uncommon, for large or complex
ontologies, that the reasoner will take a long time to initialize.
Once the reasoner has initialized it will hopefully perform much
Also, for different ontologies, different reasoners have different
performance characteristics. For example, if you click
File->Check for plugins, you will see that you can download and
install other reasoners such as the pellet and RacerPro.
If, on the other hand, the slow-down is happening after the
initialization of the reasoner completes, then there is a different
solution that is described here:
then i change to run Fact++ reasoner, and it shut down the
entire Protege tools.
This can happen because FaCT++ is written in C++ and is thus not as
stable as programs written in java. This periodically comes up as
an issue with the Protege group where we debate whether the FaCT++
plugin should be included in the Protege desktop client when it can
and does cause the Protege desktop to crash. A possible alternative
to the FaCT++ reasoner is the JFact DL reasoner whose project page
can be found here: