The matter felt familiar so I checked one of my main TWs for "sizesort" and, sure enough;
<$list filter="[!is[system]!is[shadow]!lsort[]]">
<$macrocall $name="length" tiddler={{!!title}}/>
<$link><$view field=title/></$link><br>
</$list>
Now, that "length" macro is apparently from this plugin by Thomas Elmiger:
$:/plugins/telmiger/EditorCounter/counter.js
do a search and you'll probably find it.
After those things were made, we now have a "count" filter operator. Maybe that can be used instead to not depend on that separate plugin... but on the other hand it might be much slower, I have no idea.
<:-)