Merge pull request #87961 from rhybrillou/rhybrillou/sac_performance_considerations

doc: performance considerations for large scale access scopes

Author: kcarmichael08

modules/create-a-custom-access-scope.adoc

@@ -46,3 +46,14 @@ Access to a specific namespace gives access to the following information within
 ====
 . If you want to allow access to clusters and namespaces based on labels, click *Add label selector* under the *Label selection rules* section. Then click *Add rule* to specify *Key* and *Value* pairs for the label selector. You can specify labels for clusters and namespaces.
 . Click *Save*.
+
+[id="scale-considerations_{context}"]
+== Scale considerations
+
+In large environments, for example, with thousands of namespaces, the application of user scopes that cover large numbers of namespaces can cause some pages to render slowly or time out. For example, you might experience timeouts when opening the main *Dashboard* page.
+
+Performance was tested in a single-cluster context on an environment with 20,000 deployments across 5,000 namespaces and 80,000 alerts in one test cluster. In that testing, the load time of the main *Dashboard* page for scopes including up to 2,000 namespaces on that cluster was under a few seconds.
+
+Performance was tested in a multi-cluster context on an environment with 200,000 deployments across 50,000 namespaces and 800,000 alerts across 10 test clusters. In that testing, the load time of the main *Dashboard* page was under a few seconds for scopes including up to 500 namespaces across the 10 clusters, as well as for scopes including up to 2,000 namespaces on a single cluster.
+
+The load time of {product-title-short} portal pages for user scopes with more namespaces than the numbers tested cannot be guaranteed to stay under the timeout limit.