## Bug Report Imbalanced read results in instability of sysbench select_range_point performance (-25%~8%, compared with the baseline) ### What did you do? 1. Deploy a cluster 2. Turn on prepare plan cache 3. Run sysbench select_range_point ### What did you expect to see? The TPS of multiple tests are stable. ### What did you see instead?  TPS:37778   TPS:54453   ### What version of PD are you using (`pd-server -V`)? commit ae23d409c528a836ae6d98cd174689c38ad19f2d