Question: I've tried a bunch of different setups, but I can't get it to work. Here are the two setups I was the most confident in that it would work. I simply want to map existing id's in the source to new id's that are already created in taxonomy. 

Attempt 1: 

```
  field_season:
    # Map the seasons to our already existing taxonomy terms
    -
      plugin: static_map
      source: season
      map:
        '1': 26 # Lente
        '2': 29 # Zomer
        '3': 24 # Herfst
        '4': 28 # Winter
    -
      plugin: entity_lookup
      value_key: tid
      entity_type: taxonomy_term
      bundle_key: tid
      bundle: seasons

```

Attempt 2: 

```
  field_season:
    plugin: iterator
    source: field_season
    process:
      target_id:
        # Map the seasons to our already existing taxonomy terms
        plugin: static_map
        source: season
        map:
          '1': 26 # Lente
          '2': 29 # Zomer
          '3': 24 # Herfst
          '4': 28 # Winter

```

Edit: FWIW, all the other processes work just fine!

Answer: 
load() and loadMultiple() are cached, loadByProperties() is a shortcut for an entity query + load, the entity query is not cached.

Do not use loadByProperties() if you know the entity ID.
For anyone coming across this issue;

You can also use the entity `resetCache` without passing an entity ID parameter since the `resetCache` method can accept empty parameters.
See documentation on: [EntityStorageBase::resetCache](https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Core%21Entity%21EntityStorageBase.php/function/EntityStorageBase%3A%3AresetCache/8.2.x)

```
$entity_storage = \Drupal::entityTypeManager()->getStorage('YOUR_ENTITY_NAME');
$entity_storage->resetCache(); // reset entity to clear cache
$results = $entity_storage->loadByProperties(['uid' => $uid, 'status' => 1]); // load entity data
return $results;

```