diff --git a/packages/calcite-components/src/components/combobox/combobox.e2e.ts b/packages/calcite-components/src/components/combobox/combobox.e2e.ts
index d1c7495cc06..10bda42d6ee 100644
--- a/packages/calcite-components/src/components/combobox/combobox.e2e.ts
+++ b/packages/calcite-components/src/components/combobox/combobox.e2e.ts
@@ -1214,7 +1214,7 @@ describe("calcite-combobox", () => {
         </calcite-combobox>`,
       );
 
-      const eventSpy = await page.spyOnEvent("calciteComboboxChipClose", "window");
+      const eventSpy = await page.spyOnEvent("calciteComboboxChipClose");
 
       const chip = await page.find("calcite-combobox >>> calcite-chip");
 
@@ -1235,6 +1235,7 @@ describe("calcite-combobox", () => {
         </calcite-combobox>
       `);
       const input = await page.find("calcite-combobox >>> input");
+      const eventSpy = await page.spyOnEvent("calciteComboboxChange");
 
       await input.click();
       await input.press("K");
@@ -1248,6 +1249,7 @@ describe("calcite-combobox", () => {
 
       expect((await combobox.getProperty("selectedItems")).length).toBe(1);
       expect(await item.getProperty("selected")).toBe(true);
+      expect(eventSpy).toHaveReceivedEventTimes(1);
     });
 
     it("should replace current value to new custom value in single selection mode", async () => {
@@ -1262,6 +1264,7 @@ describe("calcite-combobox", () => {
       await skipAnimations(page);
       const combobox = await page.find("calcite-combobox");
       const input = await page.find("calcite-combobox >>> input");
+      const eventSpy = await page.spyOnEvent("calciteComboboxChange");
 
       await input.click();
       await input.press("K");
@@ -1276,6 +1279,7 @@ describe("calcite-combobox", () => {
       expect((await combobox.getProperty("selectedItems")).length).toBe(1);
       expect(await customValue.getProperty("selected")).toBe(true);
       expect(await item1.getProperty("selected")).toBe(false);
+      expect(eventSpy).toHaveReceivedEventTimes(1);
     });
 
     it("should auto-select new custom values in multiple selection mode", async () => {
@@ -1289,6 +1293,7 @@ describe("calcite-combobox", () => {
       `);
       const combobox = await page.find("calcite-combobox");
       const input = await page.find("calcite-combobox >>> input");
+      const eventSpy = await page.spyOnEvent("calciteComboboxChange");
 
       await input.click();
       await input.press("K");
@@ -1306,6 +1311,7 @@ describe("calcite-combobox", () => {
       expect(await customValue.getProperty("selected")).toBe(true);
       expect(await item1.getProperty("selected")).toBe(true);
       expect(await item2.getProperty("selected")).toBe(true);
+      expect(eventSpy).toHaveReceivedEventTimes(1);
     });
   });
 
@@ -1716,7 +1722,7 @@ describe("calcite-combobox", () => {
     });
 
     it("should cycle through items on ArrowUp/ArrowDown and toggle selection on/off on Enter", async () => {
-      const eventSpy = await page.spyOnEvent("calciteComboboxChange", "window");
+      const eventSpy = await page.spyOnEvent("calciteComboboxChange");
       const item1 = await page.find("calcite-combobox-item#one");
       const item2 = await page.find("calcite-combobox-item#two");
       const item3 = await page.find("calcite-combobox-item#three");
@@ -2013,6 +2019,7 @@ describe("calcite-combobox", () => {
           <calcite-combobox-item id="three" value="three" text-label="three"></calcite-combobox-item>
         </calcite-combobox>
       `);
+      const eventSpy = await page.spyOnEvent("calciteComboboxChange");
       let chip = await page.find("calcite-combobox >>> calcite-chip");
       expect(chip).toBeNull();
 
@@ -2021,6 +2028,7 @@ describe("calcite-combobox", () => {
 
       await element.press("K");
       await element.press("Enter");
+      expect(eventSpy).toHaveReceivedEventTimes(1);
 
       chip = await page.find("calcite-combobox >>> calcite-chip");
       expect(chip).toBeDefined();
@@ -2032,6 +2040,7 @@ describe("calcite-combobox", () => {
       await element.press("Enter");
       const chips = await page.findAll("calcite-combobox >>> calcite-chip");
       expect(chips.length).toBe(1);
+      expect(eventSpy).toHaveReceivedEventTimes(2);
     });
 
     it("should fire calciteComboboxChange when entering new unknown tag", async () => {
@@ -2049,6 +2058,7 @@ describe("calcite-combobox", () => {
 
       await input.press("K");
       await input.press("Enter");
+      await page.waitForChanges();
       expect(eventSpy).toHaveReceivedEventTimes(1);
     });
 
@@ -2063,6 +2073,7 @@ describe("calcite-combobox", () => {
         <button>OK</button>
       `);
       const chip = await page.find("calcite-combobox >>> calcite-chip");
+      const eventSpy = await page.spyOnEvent("calciteComboboxChange");
       expect(chip).toBeNull();
 
       const input = await page.find("calcite-combobox >>> input");
@@ -2080,6 +2091,7 @@ describe("calcite-combobox", () => {
 
       let chips = await page.findAll("calcite-combobox >>> calcite-chip");
       expect(chips.length).toBe(1);
+      expect(eventSpy).toHaveReceivedEventTimes(1);
       await input.press("j");
 
       await page.waitForChanges();
@@ -2092,6 +2104,7 @@ describe("calcite-combobox", () => {
 
       chips = await page.findAll("calcite-combobox >>> calcite-chip");
       expect(chips.length).toBe(2);
+      expect(eventSpy).toHaveReceivedEventTimes(2);
     });
 
     it("should select known tag when input", async () => {
@@ -2104,6 +2117,7 @@ describe("calcite-combobox", () => {
         </calcite-combobox>
       `);
       let chip = await page.find("calcite-combobox >>> calcite-chip");
+      const eventSpy = await page.spyOnEvent("calciteComboboxChange");
       expect(chip).toBeNull();
 
       const input = await page.find("calcite-combobox >>> input");
@@ -2119,6 +2133,7 @@ describe("calcite-combobox", () => {
       expect(await chip.getProperty("value")).toBe("one");
       const item1 = await page.find("calcite-combobox-item#one");
       expect(await item1.getProperty("selected")).toBe(true);
+      expect(eventSpy).toHaveReceivedEventTimes(1);
     });
   });
 
@@ -2398,8 +2413,9 @@ describe("calcite-combobox", () => {
       const page = await newE2EPage();
       await page.setContent(html);
       await skipAnimations(page);
+      const openEvent = page.waitForEvent("calciteComboboxOpen");
       await page.click("calcite-combobox");
-      await page.waitForChanges();
+      await openEvent;
 
       const activeItem = await page.find("calcite-combobox-item[active]");
       expect(await activeItem.getProperty("value")).toBe(expectedActiveItemValue);
@@ -2507,12 +2523,12 @@ describe("calcite-combobox", () => {
 
     async function assertClickOutside(selectionMode = "multiple", allowCustomValues = false): Promise<void> {
       const combobox = await page.find("calcite-combobox");
+      const eventSpy = await page.spyOnEvent("calciteComboboxChange");
       combobox.setProperty("selectionMode", selectionMode);
       combobox.setProperty("allowCustomValues", allowCustomValues);
+      await page.waitForChanges();
       const inputEl = await page.find(`#myCombobox >>> input`);
-
       await inputEl.focus();
-      await page.waitForChanges();
       expect(await page.evaluate(() => document.activeElement.id)).toBe("myCombobox");
 
       const comboboxRect = await page.evaluate(() => {
@@ -2530,6 +2546,7 @@ describe("calcite-combobox", () => {
       expect(await page.evaluate(() => document.activeElement.id)).not.toBe("myCombobox");
       expect(await inputEl.getProperty("value")).toBe("");
       expect(await combobox.getProperty("value")).toBe(allowCustomValues ? "three" : "");
+      expect(eventSpy).toHaveReceivedEventTimes(allowCustomValues ? 1 : 0);
     }
 
     selectionModes.forEach((mode) => {
@@ -2558,6 +2575,7 @@ describe("calcite-combobox", () => {
 
     async function clearInputValueOnBlur(selectionMode = "multiple", allowCustomValues = false): Promise<void> {
       const combobox = await page.find("calcite-combobox");
+      const eventSpy = await page.spyOnEvent("calciteComboboxChange");
       combobox.setProperty("selectionMode", selectionMode);
       combobox.setProperty("allowCustomValues", allowCustomValues);
       const inputEl = await page.find(`#myCombobox >>> input`);
@@ -2572,6 +2590,7 @@ describe("calcite-combobox", () => {
       await page.waitForChanges();
       expect(await inputEl.getProperty("value")).toBe("");
       expect(await combobox.getProperty("value")).toBe(allowCustomValues ? "three" : "");
+      expect(eventSpy).toHaveReceivedEventTimes(allowCustomValues ? 1 : 0);
     }
 
     selectionModes.forEach((mode) => {
diff --git a/packages/calcite-components/src/components/combobox/combobox.tsx b/packages/calcite-components/src/components/combobox/combobox.tsx
index fa4d5740bb8..d74c2fdd8da 100644
--- a/packages/calcite-components/src/components/combobox/combobox.tsx
+++ b/packages/calcite-components/src/components/combobox/combobox.tsx
@@ -107,10 +107,6 @@ export class Combobox
 
   // #region Private Properties
 
-  private internalComboboxChangeEvent = (): void => {
-    this.calciteComboboxChange.emit();
-  };
-
   private allSelectedIndicatorChipEl: Chip["el"];
 
   private chipContainerEl: HTMLDivElement;
@@ -119,7 +115,9 @@ export class Combobox
 
   defaultValue: Combobox["value"];
 
-  private emitComboboxChange = debounce(this.internalComboboxChangeEvent, 0);
+  private emitComboboxChange(): void {
+    this.calciteComboboxChange.emit();
+  }
 
   private get effectiveFilterProps(): string[] {
     if (!this.filterProps) {
@@ -216,6 +214,8 @@ export class Combobox
 
   private groupData: GroupData[];
 
+  private groupItems: HTMLCalciteComboboxItemGroupElement["el"][] = [];
+
   private guid = guid();
 
   private ignoreSelectedEventsFlag = false;
@@ -224,6 +224,8 @@ export class Combobox
 
   private internalValueChangeFlag = false;
 
+  private items: HTMLCalciteComboboxItemElement["el"][] = [];
+
   labelEl: Label["el"];
 
   private listContainerEl: HTMLDivElement;
@@ -278,12 +280,6 @@ export class Combobox
 
   @state() compactSelectionDisplay = false;
 
-  @state() groupItems: HTMLCalciteComboboxItemGroupElement["el"][] = [];
-
-  @state() items: HTMLCalciteComboboxItemElement["el"][] = [];
-
-  @state() needsIcon: boolean;
-
   @state() selectedHiddenChipsCount = 0;
 
   @state() selectedVisibleChipsCount = 0;
@@ -564,7 +560,6 @@ export class Combobox
 
   async load(): Promise<void> {
     setUpLoadableComponent(this);
-    this.filterItems(this.filterText, false, false);
   }
 
   override willUpdate(changes: PropertyValues<this>): void {
@@ -611,16 +606,15 @@ export class Combobox
     }
 
     updateHostInteraction(this);
-
-    if (!this.hasUpdated) {
-      this.refreshSelectionDisplay();
-    }
+    this.refreshSelectionDisplay();
   }
 
   loaded(): void {
     afterConnectDefaultValueSet(this, this.getValue());
     connectFloatingUI(this);
     setComponentLoaded(this);
+    this.updateItems();
+    this.filterItems(this.filterText, false, false);
   }
 
   override disconnectedCallback(): void {
@@ -658,14 +652,10 @@ export class Combobox
 
   private valueHandler(value: string | string[]): void {
     if (!this.internalValueChangeFlag) {
-      const items = this.getItems();
-      if (Array.isArray(value)) {
-        items.forEach((item) => (item.selected = value.includes(item.value)));
-      } else if (value) {
-        items.forEach((item) => (item.selected = value === item.value));
-      } else {
-        items.forEach((item) => (item.selected = false));
-      }
+      this.getItems().forEach((item) => {
+        item.selected = Array.isArray(value) ? value.includes(item.value) : value === item.value;
+      });
+
       this.updateItems();
     }
   }
@@ -718,7 +708,9 @@ export class Combobox
     event: CustomEvent<HTMLCalciteComboboxItemElement["el"]>,
   ): void {
     event.stopPropagation();
-    this.updateItems();
+    if (this.hasUpdated) {
+      this.updateItems();
+    }
   }
 
   private clearValue(): void {
@@ -931,6 +923,7 @@ export class Combobox
     listContainerEl.style.inlineSize = `${referenceEl.clientWidth}px`;
     await this.reposition(true);
   }
+
   private calciteChipCloseHandler(comboboxItem: HTMLCalciteComboboxItemElement["el"]): void {
     this.open = false;
 
@@ -1229,15 +1222,20 @@ export class Combobox
     return this.filterText === "" ? this.items : this.items.filter((item) => !item.hidden);
   }
 
-  private updateItems = debounce((): void => {
+  private updateItems(): void {
     this.items = this.getItems();
     this.groupItems = this.getGroupItems();
+
     this.data = this.getData();
     this.groupData = this.getGroupData();
+
+    this.updateItemProps();
+
     this.selectedItems = this.getSelectedItems();
     this.filteredItems = this.getFilteredItems();
-    this.needsIcon = this.getNeedsIcon();
+  }
 
+  private updateItemProps(): void {
     this.items.forEach((item) => {
       item.selectionMode = this.selectionMode;
       item.scale = this.scale;
@@ -1260,7 +1258,7 @@ export class Combobox
         nextGroupItem.afterEmptyGroup = groupItem.children.length === 0;
       }
     });
-  }, DEBOUNCE.nextTick);
+  }
 
   private getData(): ItemData[] {
     return this.items.map((item) => ({
@@ -1281,10 +1279,6 @@ export class Combobox
     }));
   }
 
-  private getNeedsIcon(): boolean {
-    return isSingleLike(this.selectionMode) && this.items.some((item) => item.icon);
-  }
-
   private resetText(): void {
     if (this.textInput.value) {
       this.textInput.value.value = "";
@@ -1308,9 +1302,6 @@ export class Combobox
     if (existingItem) {
       this.toggleSelection(existingItem, true);
     } else {
-      if (!this.isMulti()) {
-        this.toggleSelection(this.selectedItems[this.selectedItems.length - 1], false);
-      }
       const item = document.createElement(
         // TODO: [MIGRATION] If this is dynamically creating a web component, please read the docs: https://qawebgis.esri.com/arcgis-components/?path=/docs/lumina-jsx--docs#rendering-jsx-outside-the-component
         "calcite-combobox-item",
@@ -1319,14 +1310,11 @@ export class Combobox
       item.heading = value;
       item.selected = true;
       this.el.prepend(item);
-      this.resetText();
+      this.toggleSelection(item, true);
+      this.open = true;
       if (focus) {
         this.setFocus();
       }
-      this.updateItems();
-      this.filterItems("");
-      this.open = true;
-      this.emitComboboxChange();
     }
   }