javascript - 'Gulp watch' event takes double the amount of time to compile less compared to normal 'gulp less' command -

i'm having issues gulp 'watch' less function in taking 2x longer compile less files compared individual less function.

when use 'gulp less' takes average of 9/10 seconds

[12:57:15] starting 'less'... [12:57:25] finished 'less' after 9.96 s 

however when use 'gulp watch-less', change file trigger watch function takes double time compared 'gulp less'.

[13:03:43] starting 'watch-less'... [13:03:45] finished 'watch-less' after 1.31 s [13:03:48] starting 'less'... [13:04:06] finished 'less' after 18 s 

below gulpfile.js pulls in 'paths.json' i've got 5 different themes (names changed question) less file being used needs outputted relevant folder why use function 'updatedestfolder'.

the way less imported change in base theme should update themes 2-5.

/*jslint node: true */ 'use strict';  // require various plugins var gulp     = require('gulp'); var watch    = require('gulp-watch'); var less     = require('gulp-less'); var plumber = require('gulp-plumber');  // pull in external paths json var paths = require('./config/paths.json');  // determine output path depending on source path function updatedestfolder(path) {     var folder = '';      if (path.indexof(paths.themes.basetheme) > -1) {         folder = paths.themedest.basetheme;     }     else if (path.indexof(paths.themes.theme2) > -1) {         folder = paths.themedest.theme2;     }     else if (path.indexof(paths.themes.theme3) > -1) {         folder = paths.themedest.theme3;     }     else if (path.indexof(paths.themes.theme4) > -1) {         folder = paths.themedest.theme4;     }     else if (path.indexof(paths.themes.theme5) > -1) {         folder = paths.themedest.theme5;     }      return folder; }  // compile less gulp.task('less', function() {     var completelesspaths = paths.less.src.concat(paths.less.ignore); // merges both arrays     var destfolder;      return gulp.src(completelesspaths)         .pipe(plumber()) // handle errors plugins         .pipe(less({             strictunits: true,             compress: true // minify style         }))         .pipe(gulp.dest(function (file) {             destfolder = updatedestfolder(file.path);             return destfolder + 'styles/';         })); });  // default tasks run when 'gulp' ran via command line gulp.task('default', ['less', 'js', 'image']);  // watch changes less source files, fire relevant function gulp.task('watch-less', function () {     gulp.watch(paths.less.src, ['less']); }); 

paths.json:

{   "less" : {     "src" : [       "../orchard.web/themes/theme1base/styles/**/*.less",       "../orchard.web/themes/theme2/styles/**/*.less",       "../orchard.web/themes/theme3/styles/**/*.less",       "../orchard.web/themes/theme4/styles/**/*.less",       "../orchard.web/themes/theme5/styles/**/*.less"     ],     "ignore" : [       "!../**/*.css",       "!../**/bootstrap-overrides.less",       "!../**/font-awesome.less",       "!../**/imports/**/*.less",       "!../**/typography*.less",       "!../**/*variables*.less"     ]   },   "themes" : {     "basetheme": "theme1base",     "theme2": "theme2",     "theme3": "theme3",     "theme4": "theme4",     "theme5": "theme5",   },   "themedest" : {     "basetheme" : "../orchard.web/themes/theme1base/",     "theme2" : "../orchard.web/themes/theme2/",     "theme3" : "../orchard.web/themes/theme3/",     "theme4": "../orchard.web/themes/theme4/",     "theme5" : "../orchard.web/themes/theme5/",   } } 

if suggest improvements of determining dest folder without needing use function i'd grateful well.

thanks

i have no idea why takes more time, here's how can determine dest folder better:

gulp.dst(function(file) { return file.split("/styles")[0] + "/styles/"; });