### Godot version

4.1

### System information

Windows 10

### Issue description

I have this config file and thought I'd try and edit it. The editor opens the .cfg file with no issue but highlighting the text crashes the editor.
Also adding and deleting text is very delayed.

This is probably a performance issue, I'm not sure if the editor would unfreeze if I waited a while.

Note:
The text highlights fine but crashes when I let go of the mouse.

### Steps to reproduce

Try highlighting some of the text from this file, I dare you!
[AStar Data.zip](https://github.com/godotengine/godot/files/12387133/AStar.Data.zip)


### Minimal reproduction project

N/A
_scroll_down(delta);
		}
		h_scroll->set_value(h_scroll->get_value() + pan_gesture->get_delta().x * 100);
		if (v_scroll->get_value() != prev_v_scroll || h_scroll->get_value() != prev_h_scroll) {
			accept_event(); 
		}
		return;
	}
	Ref<InputEventMouseMotion> mm = p_gui_input;
	if (mm.is_valid()) {
		Vector2i mpos = mm->get_position();
		if (is_layout_rtl()) {
			mpos.x = get_size().x - mpos.x;
		}
		if (mm->get_button_mask().has_flag(MouseButtonMask::LEFT) && get_viewport()->gui_get_drag_data() == Variant()) { 
			_reset_caret_blink_timer();
			if (draw_minimap && !dragging_selection) {
				_update_minimap_drag();
			}
			if (!dragging_minimap) {
				switch (selecting_mode) {
					case SelectionMode::SELECTION_MODE_POINTER: {
						_update_selection_mode_pointer();
					} break;
					case SelectionMode::SELECTION_MODE_WORD: {
						_update_selection_mode_word();
					} break;
					case SelectionMode::SELECTION_MODE_LINE: {
						_update_selection_mode_line();
					} break;