[FileChooser] Slow response issue when opening project

### Apache NetBeans version

Apache NetBeans 20 release candidate

### What happened

Clicking on the menu file ->Open Project takes about 6-8 seconds for the dialog box to pop up. Secondly, clicking on the ski bar in the project tree to browse the project file experience is not very good, resulting in slow response issues,

Selfsampler File:
[selfsampler.zip](https://github.com/apache/netbeans/files/13601430/selfsampler.zip)

### How to reproduce

_No response_

### Did this work correctly in an earlier version?

No / Don't know

### Operating System

win10

### JDK

zulu21.28.85-ca-jdk21.0.0

### Apache NetBeans packaging

Apache NetBeans binary zip

### Anything else

_No response_

### Are you willing to submit a pull request?

No

Start by reproducing the File > Open Project delay on Windows 10 with JDK 21 and reviewing the attached selfsampler.zip. Compare the dialog-opening and project-tree scrolling responsiveness before and after the investigation; done means the reported slow responses are improved and the behavior is verified.

Written by the indexing model from the issue text.