Performance delay when typing each letter into the ComboBox when the ItemsSource has 40,000 items

### Description

When loading 40,000 complex objects and setting the DisplayMemberPath, there is a delay between the keystroke and the update of the letter in the ComboBox control. Please find the code snippet below.

**XAML codes:**

```

```
**C# Code:**

```
public class ComboBoxObject
{
public string DisplayText { get; set; }
public int Index { get; set; }
}
```
**Video output:**

https://github.com/user-attachments/assets/c6434c23-ec2f-4344-9d76-b0ac482d187e

**Tested Sample:**
[ComboBox_Demo.zip](https://github.com/user-attachments/files/16458873/ComboBox_Demo.zip)

### Reproduction Steps

1. Run the sample.
2. Enter letters into the second ComboBox which has no DisplayMemberPath property (no delay).
3. Enter letters into the first ComboBox which has DisplayMemberPath property set (experiencing delay).

### Expected behavior

There should not be a delay when entering a letter into the ComboBox control.

### Actual behavior

There should be a delay when entering a letter into the ComboBox control.

### Regression?

_No response_

### Known Workarounds

_No response_

### Impact

_No response_

### Configuration

_No response_

### Other information

_No response_