This situation is handled by a PTF:
APAR #: RO94494
Product: FMMVS Release: 10.0
Title: HIGH CPU UTILIZATION IN GRS
Browsing or Editing a dataset can cause high CPU utilization for the
GRS component of z/OS.
When attempting to Browse or Edit a dataset the user's session can
hang and the system shows high CPU utilization for the GRS component
The user cannot Browse or Edit the dataset.
In some cases if the dataset is in use by another task or user,
releasing the dataset from that task or user may resolve the problem.