With https://issues.jboss.org/browse/RESTEASY-1983, the client configuration is inherited and detached from parent. This is per JAX-RS spec. However, deep copying all the configuration each time a new `Webtarget` is created even when there is no configuration difference between parent and child gets quite costly. In our internal testing, we identified significant memory pressure because of this, which impacts our 99th percentile latency.
Please see the PR https://github.com/resteasy/Resteasy/pull/2107.