When editing very large xml files, adding a / to a tag cause np++ to become irresponsive

Damn this markup, how do I escape it? Where I place a {, it is a < in reality.

Description of the Issue

When editing a large xml file, removing a large part, editing some text, searching, all no problem. but for example:

{MyList>
{li>
[blah]
{/li>
{ /Mylist>

removing all lines from {li> until (including) {/mylist> goes fine. So I want to change {MyList> to {MyList />
I add the space, no problem. Touch the /, np++ goes irresponsive. This does not always happen, I can't say when it will.

Steps to Reproduce the Issue

1. get the file from me, select XML as filetype
2. search for the tag
3. add a /

Expected Behavior

a / to appear where the cursor is

Actual Behavior

the program becomes irresponsive

Debug Information

Notepad++ v8.1.9.1 (64-bit)
Build time : Nov 13 2021 - 15:28:20
Path : C:\Program Files\Notepad++\notepad++.exe
Command Line :
Admin mode : OFF
Local Conf mode : OFF
Cloud Config : OFF
OS Name : Windows 10 Pro (64-bit)
OS Version : 2009
OS Build : 19043.1348
Current ANSI codepage : 1252
Plugins : ComparePlugin.dll mimeTools.dll NppConverter.dll NppExport.dll NppFTP.dll NppToolBucket.dll NppXmlTreeviewPlugin.dll

No source file or test is named. First reproduce the freeze using a very large XML file in XML mode and the reported search-and-edit steps; compare behavior when adding the slash. Done means the slash appears at the cursor and Notepad++ remains responsive.