I was looking at a flame graph of an ingestion workload with @dliappis, and it looks like we parse the JSON representation of the index request twice when a document has both a pipeline and a final pipeline.

It's hard to know how much we would save on this benchmark since not all data streams in this benchmark had both a pipeline and a final pipeline, but the cost of parsing index request into maps of maps via IngestService represented 4.06% of overall CPU time according to the flame graph, so this might not be negligible.
server/src/main/java/org/elasticsearch/ingest/IngestService.java
);
                }
                final Integer currentVersion = currentPipeline.getVersion();
                if (Objects.equals(request.getVersion(), currentVersion) == false) {
                    throw new IllegalArgumentException(
                        String.format(
                            Locale.ROOT,
                            "version conflict, required version [%s] for pipeline [%s] but current version is [%s]",
                            request.getVersion(),
                            request.getId(),
                            currentVersion
                        )
                    );
                }
                var pipelineConfig = XContentHelper.convertToMap(request.getSource(), false, request.getXContentType()).v2();
                final Integer specifiedVersion = (Integer) pipelineConfig.get("version");
                if (pipelineConfig.containsKey("version") && Objects.equals(specifiedVersion, currentVersion)) {
                    throw new IllegalArgumentException(
                        String.format(
                            Locale.ROOT,
                            "cannot update pipeline [%s] with the same version [%s]",
                            request.getId(),
                            request.getVersion()
                        )
                    );
                }
                
                if (specifiedVersion == null) {
                    pipelineConfig.put("version", request.getVersion() == null ? 1 : request.getVersion() + 1);
                    try {