Performing any long running task or CPU intensive work on transport_worker threads is problematic. This is typically very bad for cluster stability.

This issue has been filed to examine the usage of transport_worked threads by ESQL, with the intention of "offloading" as much as possible, including deserialising large(ish) amounts of data.
x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plugin/ComputeService.java
private static final Logger LOGGER = LogManager.getLogger(ComputeService.class);
    private final SearchService searchService;
    private final BigArrays bigArrays;
    private final TransportService transportService;
    private final DriverTaskRunner driverRunner;
    private final ExchangeService exchangeService;
    private final EnrichLookupService enrichLookupService;
    public ComputeService(
        SearchService searchService,
        TransportService transportService,
        ExchangeService exchangeService,
        EnrichLookupService enrichLookupService,
        ThreadPool threadPool,
        BigArrays bigArrays
    ) {
        this.searchService = searchService;
        this.transportService = transportService;
        this.bigArrays = bigArrays.withCircuitBreaking();
        transportService.registerRequestHandler(
            DATA_ACTION_NAME,