as i understand it as soon as one adds the second thread (and for any further one) a worker thread is created, which is doing all the work and spinning idle when there is nothing to be done - as a result all worker threads are looking like at about 100% cpu usage, but as the idle spinning is done in a clever way, it should not result in any extra heat etc. … so only add extra threads when the current number of threads cannot handle the load anymore and don’t be surprised that any extra worker thread immediately seems to consume nearly 100% cpu (at least under linux it looks like this)
best wishes - hexdump