Some thoughts on performance

[saqimtiaz]

@Yaisog

since the content assigned to filter-definition is just a (constant) string and not the filter result, this use of subfilter<filter-definition> will not result in the destruction of the $list (as a child of $let) when the actual result of the subfilter changes?

Correct.

@Yaisog

However, the scope of \define is the whole tiddler – so when the output of the macro changes, everything in the tiddler is destroyed and re-rendered?

Unless the \define is in another tiddler, I don’t see how it can change without re-rendering the entire tiddler anyway.

If the macro is defined in another tiddler and either global or imported using $importvariables then yes, any change in it will refresh the entire tiddler it is being imported into.

Keep in mind that macros return strings, i.e. the wikitext is not processed. So if you are not using string substitution in your macro, you never have to worry about it changing.