Sluggishness when active, but fast when not as active window.

Description of the Issue

When I opened a very long lines of code, I experience sluggishness when it is as active window.
But when I scroll Notepad++ as background window, it fast.

Steps to Reproduce the Issue

1. Open a very long lines of code
2. Open it as active window, no other window on top of that
3. Scroll your cursor using mouse.
4. Try open Task Manager on top of it
5. Try scrolling again without making Notepad++ to foreground
6. it really fast.

Expected Behavior

Keep fast.

Actual Behavior

Slow when scrolling.

Debug Information

Notepad++ v8.4.6 (64-bit)
Build time : Sep 25 2022 - 19:51:39
Path : C:\Program Files\Notepad++\notepad++.exe
Command Line :
Admin mode : OFF
Local Conf mode : OFF
Cloud Config : OFF
OS Name : Windows 11 (64-bit)
OS Version : 21H2
OS Build : 22000.1219
Current ANSI codepage : 1252
Plugins :
mimeTools (2.8)
NppConverter (4.4)
NppExport (0.4)

Start by reproducing the scrolling comparison with a very long line while Notepad++ is foregrounded and while Task Manager is on top, using the reported Notepad++ and Windows versions. Compare the behavior and gather the missing diagnostics needed to identify the responsible code; done means active-window scrolling is no longer sluggish.