dlopen() and dlclose() and History

Probes in shared objects that are brought in by a dlopen(3X) are automatically set up according to the prex command history. When a shared object is removed by a dlclose(3X), prex refreshes its understanding of the probes in the target program. This implies that there is more work to do for dlopen and dlclose, so they take slightly longer.

If you are not interested in this feature and don't want dlopen and dlclose to be perturbed, detach prex from the target.