### Bug or Regression

- An inefficient lock in EndpointSlice controller metrics cache has been reworked. Network programming latency may be significantly reduced in certain scenarios, especially in clusters with a large number of Services. ([#107169](https://github.com/kubernetes/kubernetes/pull/107169), [@robscott](https://github.com/robscott)) [SIG Apps and Network]

- Cleanup subnet in frontend IP configs to prevent huge subnet request bodies in some scenarios. ([#98290](https://github.com/kubernetes/kubernetes/pull/98290), [@nilo19](https://github.com/nilo19)) [SIG Cloud Provider]

## Before Upgrading

Consider the following changes, limitations, and guidelines before you upgrade:

### **API Machinery**

  never enter the Succeeded phase may need to adapt their controllers. This is because as a consequence of 
  the change pods which use RestartPolicy=Always may end up in the Succeeded phase in two scenarios: pod 
  deletion and graceful node shutdown. ([#115331](https://github.com/kubernetes/kubernetes/pull/115331), [@mimowo](https://github.com/mimowo)) [SIG Cloud Provider, Node and Testing]

* kubeadm: fix a possible panic when joining a new control plane node in HA scenarios ([#72123](https://github.com/kubernetes/kubernetes/pull/72123), [@anitgandhi](https://github.com/anitgandhi))

- The scheduling queue didn't notice any extenders' failures, it could miss some cluster events,
  and it could end up Pods rejected by Extenders stuck in unschedulable pod pool in 5min in the worst-case scenario.
  Now, the scheduling queue notices extenders' failures and requeue Pods rejected by Extenders appropriately. ([#122045](https://github.com/kubernetes/kubernetes/pull/122045), [@sanposhiho](https://github.com/sanposhiho)) [SIG Scheduling]

* [GCE] Enable by default audit logging truncating backend. ([#68288](https://github.com/kubernetes/kubernetes/pull/68288), [@loburm](https://github.com/loburm))
* kubeadm: fix a possible scenario where kubeadm can pull much newer control-plane images ([#69301](https://github.com/kubernetes/kubernetes/pull/69301), [@neolit123](https://github.com/neolit123))

more information, see [#53356](https://issue.k8s.io/53356#issuecomment-333748618).

* A performance issue was identified in large-scale clusters when deleting thousands of pods simultaneously across hundreds of nodes. Kubelets in this scenario can encounter temporarily increased latency of `delete pod` API calls -- above the target service level objective of 1 second. If you run clusters with this usage pattern and if pod deletion latency could be an issue for you, you might want to wait...

### SIG OpenStack

SIG-OpenStack continued to build out testing, with eleven acceptance tests covering a wide-range of scenarios and use-cases. During the 1.11 cycle our reporting back to test-grid has qualified the OpenStack cloud provider as a gating job for the Kubernetes release.

- QueueingHint implementation for NodeAffinity is reverted because we found potential scenarios where events that make Pods schedulable could be missed. ([#122327](https://github.com/kubernetes/kubernetes/pull/122327), [@sanposhiho](https://github.com/sanposhiho)) [SIG Scheduling]