ElasticSearch _bulk and _update got bad performance

Elastic Stack Elasticsearch
1

I'm using _bulk request and updating documents by doc. However, some complex cases need to apply script for updating.

However, the performance in case script is very bad. It affects search side and index side latency.

Is there any bottleneck between update by script and update by doc?

2

Which version of Elasticsearch are you using? What is the size and structure of your documents? Are you using nested mappings? If so, how many nested object does an average document have?