Performance when iterating over deeply nested items

[hanneshoepfnerio]

Hi I've experienced some very poor loading times most probably due to my very poor code logic ;)
I solved it in another way, but I wanted to check with you if I did some major mistakes in my old approach and how it could be this slow.

So the setup was:
A collection "post", which could holds multiple images "img" which could hold multiple taxonomies "tax".

At some point in the code I needed:
For each tax, all posts which had an image which hat the same taxonomy.

I wrote a modifier where I was passing in the collection and the taxonomy. Filtering the post collection, gathering all the images, checking for its taxonomy.
It resulted in TTFB at around 2-3seconds.

Here is an abstract code example:

// template

  {{taxonomy from="tax" as="tax" }}
            {{ tax  }}
                       {{ items = {collection:posts} | img_tag_filter({slug}) | shuffle | limit:3 }}
                        

                        {{/items}}
            {{ /tax  }}
        {{/taxonomy }}

//  img_tag_filter modifier
 public function index($value, $params, $context)
    {
        if(!$params) return;

        $filterTag = $params[0];
        debug("original value",$value);
        $value = collect($value);
  
        $filteredResults = $value->filter(function ($item) use ($filterTag) {
            $assets = $item->toAugmentedCollection()->get('multi_image')->value()->get();

            for ($i=0; $i < count($assets); $i++) {
                $asset = $assets[$i];
                $repres = $asset->get('representative');

                if(!$repres) continue; 
  
                if(in_array($filterTag, $repres)) {
                    $item->set('reprev_img', $asset);
                    return true; 
                }
            }
        })
        ->values()->all() ;


        return $filteredResults;
    }

With this approach I was not able to get any acceptable results.

I solved it writing an event listener for the assets save event.
When ever this would happen I iterated over the post and added the sum of the unique to the post itself.
Now I can just use the taxonomy entries functionality.

 {{ taxonomy:tax }}
            {{ entries }}
            {{ /entries }}
 {{/taxonomy:tax }}            
        

like so:

public function handle(AssetSaved $event)
    {
        $allSeries = Entry::query()
        ->where('collection', 'posts') 
        ->get();

        foreach ($allSeries as $item) {
            $assets = $item->toAugmentedCollection()->get('multi_image')->value()->get();
            $represSum = [];

            foreach ($assets as $asset) {
                $repres = $asset->get('representative');
                if(!$repres) continue; 
                $represSum = [...$represSum, ...$repres];                                        
            }
            
            $represUnique = array_unique($represSum);
            $item->set('directory', $represUnique);
            $item->save();
        }

     
        $event->asset;
    }

I was just wondering if this is a total valid approach on solving this, or if it is utterly verbose?

Thanks

[hanneshoepfnerio]

Hello, short update on this topic.
It turned out that the bottleneck regarding performance was the glide tag in the template.
Besides to a slow performing nested iterations generating the glide URLs were the main reason for the poor performance.
Still trying to solve it though.