Lucene takes around 5 minutes to index 14million documents - any way to optimize it?

I have a file containing 14 million records each with 2 fields. I had indexed the documents with below config:

private fun getIndexWriter(directory: String): IndexWriter = try {
        val indexWriterConfig = IndexWriterConfig(KeywordAnalyzer())
        indexWriterConfig.ramBufferSizeMB = 2048.0
        indexWriterConfig.openMode = IndexWriterConfig.OpenMode.CREATE_OR_APPEND
        IndexWriter(FSDirectory.open(Paths.get(directory)), indexWriterConfig)
    } catch (exception: Exception) {
        logger.error("File missing: {} ", exception.message)
        throw Exception("File missing: ${exception.message}")
    }


fun indexDocs(documents: List<Document>)= mutex.withLock {
        coroutineScope {
            val indexedDocs = getIndexWriter("directory_path").use { indexWriter ->
                try {
                    documents.forEach { document ->
                        try {
                            indexWriter.addDocument(document)
                        } catch (exception: IOException) {
                            logger.error("Failed to add document: {} to passive index", document)
                        }
                    }
                    indexWriter.flush()
                    indexWriter.commit()
                } catch (exception: IOException) {
                    logger.error("Failed to commit")
                }
                indexWriter.docStats.numDocs
            }
        }
    }

It takes 5 minutes around to complete the index and to start the application, however I wanted to check if there can be some optimization done to reduce the time taken for indexing.

Thanks for the help in advance!