parallelStream（）比stream（）慢

Question

我的这段代码运行缓慢

userMenus
                .forEach(
                        ccy -> configuredAlerts
                                .add(new ConfiguredAlerts(
                                        ccy, Stream
                                                .concat(pricealertsXMenu.stream()
                                                        .filter(pac -> pac.getMenu().equals(ccy))

                                                        .map(pac -> new MenuAlarm("priceAlert",pac.getPriceAlert().getMenuAlertGroup().getName()))
                                                        .distinct(),

                                                        percentagealertsXMenu.stream()
                                                        .filter(pac -> pac.getMenu().equals(ccy))
                                                                .map(pac -> new MenuAlarm("percentageAlert",pac.getPercentageAlert().getMenuAlertGroup().getName()))
                                                                .distinct())

                                                .distinct().collect(toList()))));

我将.stream（）替换为.parallelStream（）以使其更快，但运行速度甚至更慢