### Elasticsearch Version

8.11+

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

any

### Problem Description

While indexing documents with dynamically added fields, if multiple of those fields are objects are are deeper than 3-5 objects, performance is degraded significantly.

This bug was introduced in: https://github.com/elastic/elasticsearch/pull/90674

### Steps to Reproduce

I built a micro-benchmark to replicate this particular bug. 

But, any dynamic object parsing will cause this.

To mitigate the issue, statically mapped fields for objects is required. 

### Logs (if relevant)

Attached are two JFR files indicating the difference between when the bug was introduce vs. not.
[Archive 2.zip](https://github.com/elastic/elasticsearch/files/13569248/Archive.2.zip)

server/src/main/java/org/elasticsearch/index/mapper/DocumentParserContext.java
* because for dynamic mappings, a new field can be either mapped
     * as runtime or indexed, but never both.
     */
    final void addDynamicRuntimeField(RuntimeField runtimeField) {
        if (newFieldsSeen.add(runtimeField.name())) {
            mappingLookup.checkFieldLimit(indexSettings().getMappingTotalFieldsLimit(), newFieldsSeen.size());
        }
        dynamicRuntimeFields.add(runtimeField);
    }
    /**
     * Get dynamic runtime fields created while parsing. Holds a flat set of {@link RuntimeField}s.
     * Runtime fields get dynamically mapped when {@link org.elasticsearch.index.mapper.ObjectMapper.Dynamic#RUNTIME} is used,
     * or when dynamic templates specify a <code>runtime</code> section.
     */
    public final List<RuntimeField> getDynamicRuntimeFields() {
        return Collections.unmodifiableList(dynamicRuntimeFields);
    }
    /**
     * Returns an Iterable over all non-root documents. If there are no non-root documents
     * the iterable will return an empty iterator.
     */
    public abstract Iterable<LuceneDocument> nonRootDocuments();
    /**
     * @return a RootObjectMapper.Builder to be used to construct a dynamic mapping update
     */
    public final RootObjectMapper.Builder updateRoot() {
        return mappingLookup.getMapping().getRoot().newBuilder(mappingParserContext.getIndexSettings().getIndexVersionCreated());
    }
    public boolean isWithinCopyTo() {
        return false;