返回流的Gulp任务会随着时间的推移而变慢

Question

我和Gulp一直有一个奇怪的问题。首先来看我的gulpfile：

var gulp = require('gulp'),
    rename = require('gulp-rename'),
    plumber = require('gulp-plumber'),
    connect = require('gulp-connect'),
    watch = require('gulp-watch'),
    less = require('gulp-less'),
    lessPluginAutoprefix = require('less-plugin-autoprefix'),
    minifyCSS = require('gulp-minify-css');

autoprefix = new lessPluginAutoprefix({browsers: ["> 0%"] });

gulp.task('webserver', function() {
    connect.server({
        port: 8000,
        livereload: true,
        root: ['src']
    });
});

gulp.task('livereload', function() {
    var watchedFiles = [
        'src/html/**/*.html',
        'src/style/**/*min.css',
        'src/javascript/**/*.js'
    ];
    gulp
        .src(watchedFiles)
        .pipe(watch(watchedFiles))
        .pipe(connect.reload());
});

gulp.task('less', function() {
    return gulp
        .src('src/style/less/main.less')
        .pipe(plumber(function(err) {
            console.log(err.toString());
            this.emit('end');
        }))
        .pipe(less({
            plugins: [autoprefix]
        }))
        .pipe(gulp.dest('src/style'));
});

gulp.task('minifyCSS', ['less'], function() {
    return gulp
        .src(['src/style/**/*.css', '!./src/style/**/*.min.*'])
        .pipe(minifyCSS({advanced: true}))
        .pipe(rename({suffix: '.min'}))
        .pipe(gulp.dest('src/style'));

});

gulp.task('watch', function() {
    gulp
        .watch('src/style/less/**/*.less', ['less', 'minifyCSS']);
});

gulp.task('default', ['less', 'minifyCSS', 'webserver', 'livereload', 'watch']);

正如您所看到的，这是一个简单的项目，它可以设置Web服务器，监视某些文件，并相应地执行较少的编译或Web服务器重新加载。一切运行正常，除了返回流的任务（less和minifyCSS），随着时间的推移变得越来越慢，让我在一些观察文件被修改后显示执行时间：

[11:58:24] Starting 'less'...                 
[11:58:24] Finished 'less' after 67 ms        
[11:58:24] Starting 'minifyCSS'...            
[11:58:24] Finished 'minifyCSS' after 56 ms   
[11:58:25] Starting 'less'...                 
[11:58:25] Finished 'less' after 126 ms       
[11:58:25] Starting 'minifyCSS'...            
[11:58:26] Finished 'minifyCSS' after 319 ms  
[11:58:26] Starting 'less'...                 
[11:58:27] Finished 'less' after 138 ms       
[11:58:27] Starting 'minifyCSS'...            
[11:58:27] Finished 'minifyCSS' after 121 ms  
[11:58:29] Starting 'less'...                 
[11:58:29] Finished 'less' after 227 ms       
[11:58:29] Starting 'minifyCSS'...            
[11:58:29] Finished 'minifyCSS' after 263 ms  
[11:58:30] Starting 'less'...                 
[11:58:30] Finished 'less' after 176 ms       
[11:58:30] Starting 'minifyCSS'...            
[11:58:30] Finished 'minifyCSS' after 226 ms  
[11:58:31] Starting 'less'...                 
[11:58:32] Finished 'less' after 370 ms       
[11:58:32] Starting 'minifyCSS'...            
[11:58:32] Finished 'minifyCSS' after 271 ms  
[11:58:33] Starting 'less'...                 
[11:58:33] Finished 'less' after 135 ms       
[11:58:33] Starting 'minifyCSS'...            
[11:58:33] Finished 'minifyCSS' after 277 ms  
[11:58:34] Starting 'less'...                 
[11:58:35] Finished 'less' after 240 ms       
[11:58:35] Starting 'minifyCSS'...            
[11:58:35] Finished 'minifyCSS' after 552 ms  
[11:58:36] Starting 'less'...                 
[11:58:36] Finished 'less' after 159 ms       
[11:58:36] Starting 'minifyCSS'...            
[11:58:36] Finished 'minifyCSS' after 382 ms  
[11:58:37] Starting 'less'...                 
[11:58:38] Finished 'less' after 344 ms       
[11:58:38] Starting 'minifyCSS'...            
[11:58:38] Finished 'minifyCSS' after 603 ms  
[11:58:39] Starting 'less'...                 
[11:58:39] Finished 'less' after 186 ms       
[11:58:39] Starting 'minifyCSS'...            
[11:58:40] Finished 'minifyCSS' after 492 ms  
[11:58:41] Starting 'less'...                 
[11:58:41] Finished 'less' after 414 ms       
[11:58:41] Starting 'minifyCSS'...            
[11:58:42] Finished 'minifyCSS' after 665 ms  
[11:58:42] Starting 'less'...                 
[11:58:42] Finished 'less' after 312 ms       
[11:58:42] Starting 'minifyCSS'...            
[11:58:43] Finished 'minifyCSS' after 551 ms  
[11:58:44] Starting 'less'...                 
[11:58:45] Finished 'less' after 365 ms       
[11:58:45] Starting 'minifyCSS'...            
[11:58:45] Starting 'less'...                 
[11:58:46] Finished 'minifyCSS' after 1.07 s  
[11:58:46] Finished 'less' after 358 ms       
[11:58:47] Starting 'less'...                 
[11:58:48] Finished 'less' after 415 ms       
[11:58:48] Starting 'minifyCSS'...            
[11:58:49] Finished 'minifyCSS' after 971 ms

它越来越慢，修改任何文件需要很长时间才能在浏览器中刷新，这可能是什么问题？

最好的问候。