diff --git a/frontend/src/framework/EnsembleSet.ts b/frontend/src/framework/EnsembleSet.ts
index 604eb3acc..4c75a86e9 100644
--- a/frontend/src/framework/EnsembleSet.ts
+++ b/frontend/src/framework/EnsembleSet.ts
@@ -7,10 +7,14 @@ import { isEnsembleIdentOfType } from "./utils/ensembleIdentUtils";
 export class EnsembleSet {
     private _regularEnsembleArray: RegularEnsemble[];
     private _deltaEnsembleArray: DeltaEnsemble[];
+    private _allEnsemblesArray: (RegularEnsemble | DeltaEnsemble)[];
 
     constructor(ensembles: RegularEnsemble[], deltaEnsembles: DeltaEnsemble[] = []) {
         this._regularEnsembleArray = ensembles;
         this._deltaEnsembleArray = deltaEnsembles;
+
+        // Precomputed for reference stability across renders
+        this._allEnsemblesArray = [...ensembles, ...deltaEnsembles];
     }
 
     /**
@@ -58,7 +62,7 @@ export class EnsembleSet {
      * @returns An array of all ensembles in the set.
      */
     getEnsembleArray(): readonly (RegularEnsemble | DeltaEnsemble)[] {
-        return [...this._regularEnsembleArray, ...this._deltaEnsembleArray];
+        return this._allEnsemblesArray;
     }
 
     /**
diff --git a/frontend/src/framework/components/EnsembleDropdown/ensembleDropdown.tsx b/frontend/src/framework/components/EnsembleDropdown/ensembleDropdown.tsx
index b56b38090..28a5b8636 100644
--- a/frontend/src/framework/components/EnsembleDropdown/ensembleDropdown.tsx
+++ b/frontend/src/framework/components/EnsembleDropdown/ensembleDropdown.tsx
@@ -30,6 +30,20 @@ export type EnsembleDropdownProps = (
 export function EnsembleDropdown(props: EnsembleDropdownProps): JSX.Element {
     const { onChange, ensembles, allowDeltaEnsembles, value, ensembleRealizationFilterFunction, ...rest } = props;
 
+    const optionsArray = React.useMemo<DropdownOption[]>(() => {
+        return ensembles.map((ens) => ({
+            value: ens.getIdent().toString(),
+            label: ens.getDisplayName(),
+            adornment: (
+                <EnsembleColorTile
+                    ensemble={ens}
+                    ensembleRealizationFilterFunction={ensembleRealizationFilterFunction}
+                    wrapperClassName="w-7 h-7"
+                />
+            ),
+        }));
+    }, [ensembles, ensembleRealizationFilterFunction]);
+
     const handleSelectionChange = React.useCallback(
         function handleSelectionChange(selectedEnsembleIdentStr: string) {
             const foundEnsemble = ensembles.find(
@@ -52,20 +66,5 @@ export function EnsembleDropdown(props: EnsembleDropdownProps): JSX.Element {
         [allowDeltaEnsembles, ensembles, onChange],
     );
 
-    const optionsArray: DropdownOption[] = [];
-    for (const ens of ensembles) {
-        optionsArray.push({
-            value: ens.getIdent().toString(),
-            label: ens.getDisplayName(),
-            adornment: (
-                <EnsembleColorTile
-                    ensemble={ens}
-                    ensembleRealizationFilterFunction={ensembleRealizationFilterFunction}
-                    wrapperClassName="w-7 h-7"
-                />
-            ),
-        });
-    }
-
     return <Dropdown options={optionsArray} value={value?.toString()} onChange={handleSelectionChange} {...rest} />;
 }
diff --git a/frontend/src/framework/components/EnsemblePicker/ensemblePicker.tsx b/frontend/src/framework/components/EnsemblePicker/ensemblePicker.tsx
index 7acdc2e6b..eea6d0f43 100644
--- a/frontend/src/framework/components/EnsemblePicker/ensemblePicker.tsx
+++ b/frontend/src/framework/components/EnsemblePicker/ensemblePicker.tsx
@@ -31,18 +31,16 @@ export type EnsemblePickerProps = (
 export function EnsemblePicker(props: EnsemblePickerProps): JSX.Element {
     const { onChange, ensembles, value, allowDeltaEnsembles, ensembleRealizationFilterFunction } = props;
 
-    const optionsArray: TagOption[] = [];
-    for (const ens of ensembles) {
-        optionsArray.push({
+    const selectedArray = React.useMemo<string[]>(() => {
+        return value.map((ident) => ident.toString());
+    }, [value]);
+
+    const optionsArray = React.useMemo<TagOption[]>(() => {
+        return ensembles.map((ens) => ({
             value: ens.getIdent().toString(),
             label: ens.getDisplayName(),
-        });
-    }
-
-    const selectedArray: string[] = [];
-    for (const ident of value) {
-        selectedArray.push(ident.toString());
-    }
+        }));
+    }, [ensembles]);
 
     const handleSelectionChange = React.useCallback(
         function handleSelectionChanged(selectedEnsembleIdentStringArray: string[]) {
diff --git a/frontend/src/framework/components/EnsembleSelect/ensembleSelect.tsx b/frontend/src/framework/components/EnsembleSelect/ensembleSelect.tsx
index 1079f4223..f0cccc6f4 100644
--- a/frontend/src/framework/components/EnsembleSelect/ensembleSelect.tsx
+++ b/frontend/src/framework/components/EnsembleSelect/ensembleSelect.tsx
@@ -35,6 +35,24 @@ export function EnsembleSelect(props: EnsembleSelectProps): JSX.Element {
     const { onChange, ensembles, value, allowDeltaEnsembles, multiple, ensembleRealizationFilterFunction, ...rest } =
         props;
 
+    const selectedArray = React.useMemo<string[]>(() => {
+        return value.map((ident) => ident.toString());
+    }, [value]);
+
+    const optionsArray = React.useMemo<SelectOption[]>(() => {
+        return ensembles.map((ens) => ({
+            value: ens.getIdent().toString(),
+            label: ens.getDisplayName(),
+            adornment: (
+                <EnsembleColorTile
+                    ensemble={ens}
+                    ensembleRealizationFilterFunction={ensembleRealizationFilterFunction}
+                    wrapperClassName="w-6 h-6"
+                />
+            ),
+        }));
+    }, [ensembles, ensembleRealizationFilterFunction]);
+
     const handleSelectionChange = React.useCallback(
         function handleSelectionChanged(selectedEnsembleIdentStringArray: string[]) {
             const identArray: (RegularEnsembleIdent | DeltaEnsembleIdent)[] = [];
@@ -62,35 +80,13 @@ export function EnsembleSelect(props: EnsembleSelectProps): JSX.Element {
         [allowDeltaEnsembles, ensembles, onChange],
     );
 
-    const optionsArray: SelectOption[] = [];
-    for (const ens of ensembles) {
-        optionsArray.push({
-            value: ens.getIdent().toString(),
-            label: ens.getDisplayName(),
-            adornment: (
-                <EnsembleColorTile
-                    ensemble={ens}
-                    ensembleRealizationFilterFunction={ensembleRealizationFilterFunction}
-                    wrapperClassName="w-6 h-6"
-                />
-            ),
-        });
-    }
-
-    const selectedArray: string[] = [];
-    for (const ident of value) {
-        selectedArray.push(ident.toString());
-    }
-
-    const isMultiple = multiple ?? true;
-
     return (
         <Select
             options={optionsArray}
             value={selectedArray}
             optionHeight={30}
             onChange={handleSelectionChange}
-            multiple={isMultiple}
+            multiple={multiple ?? true}
             {...rest}
         />
     );