Steps to Reproduce

run shadow-if-perf.zul
click "notifyChange pojo.shown"

Current Result

the content of the <if> shadow element re-renders on notify change, even if the condition doesn't change

Frequent unnecessary re-rendering of conditional content can lead to significant performance impact.

Expected Result

only remove/render the content when the condition changes

Debug Info

the replacement of the content can be observed by the updated component uuid and in the network response
this behaved as expected up to 8.5.0

Workaround

Replace the <if> element with an <apply> and a dynamic template

instead of:

<if test="@load(vm.shown)">
    <div>
        <label value="${self.parent.toString()}"/>
    </div>
</if>

use:

<apply template="@load(vm.shown ? 'shown' : null)">
    <template name="shown">
        <div>
            <label value="${self.parent.toString()}"/>
        </div>
    </template>
</apply>

or shorter (using the implicit template named '' (empty string)):

<apply template="@load(vm.shown ? '' : null)">
    <div>
        <label value="${self.parent.toString()}"/>
    </div>
</apply>