[Bug]: textbox of search window cause whole notepad3 freezing

[NewUserHa]

Notepad3 version

7.26.426.1

Build / architecture

x64

Windows version & build

WIN10 21H2

Last known good Notepad3 version (regression only)

No response

Steps to reproduce

1. copy some long content
2. paste into notepad3 and to search
3. press Ctrl+F
4. the whole notepad3 window frezzing for many seconds

Expected behavior

No latency.

Actual behavior

the whole notepad3 window frezzing for many seconds

Additional context

The copying from notepad3 or other places, and pasting into notepad3, then immediately starting to find in text (C-F) is a common operate, it should not block the UI thread of its process.

Version & system info (paste from About dialog)

Confirmation

• I searched existing issues and this is not a duplicate.
• I can reproduce this on a clean install (or a fresh INI via Notepad3 /i), not only with my customized config.
• If attaching Notepad3.ini: I've reviewed it for sensitive entries ([Recent Files], [Recent Find], [Recent Replace], Favorites=, DefaultDirectory=) and redacted what I don't want to share publicly.