Description of the Issue

I had need to use the Open all feature in the right-click context menu of the Search results window.
I had previously done a search which resulted in (3055 hits in 12 files of 31 searched).
The largest file containing a hit was 197157 bytes.
Unfortunately I can't provide my fileset as the files contain proprietary data belonging to my employer.

Steps to Reproduce the Issue

1. Do a Find in Files search that is representative of the above.
2. Right-click in the Search results window.
3. Choose Open all from the context menu.

Actual Behavior

It took Notepad++ roughly one minute to open the twelve files.
During that minute, the tab bar and the status bar was observed to be flickering.

Expected Behavior

I expect Notepad++ to be able to open twelve moderately-sized files relatively quickly.
I don't expect to see flickering in the tab bar and status bar areas.

Debug Information

Notepad++ v7.9.5 (64-bit)
Build time : Mar 21 2021 - 02:13:17
Path : C:..............\npp.7.9.5.portable.x64\notepad++.exe
Admin mode : OFF
Local Conf mode : ON
OS Name : Windows 10 Enterprise (64-bit)
OS Version : 1909
OS Build : 18363.1440
Current ANSI codepage : 1252
Plugins : mimeTools.dll NppConverter.dll NppExport.dll