diff --git a/.gitignore b/.gitignore
index 4ceb64ef9c..a6277425e7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,6 +18,7 @@ node_modules/
 local/
 ui/*/npm-debug.log
 hs_*.log
+yarn-error.log
 
 RUNNING_PID
 
diff --git a/ui/gulpfile.js b/ui/gulpfile.js
index 289bd373b3..fa1d8a70ae 100644
--- a/ui/gulpfile.js
+++ b/ui/gulpfile.js
@@ -2,7 +2,11 @@ const gulp = require('gulp');
 const sass = require('gulp-sass');
 const sourcemaps = require('gulp-sourcemaps');
 const autoprefixer = require('gulp-autoprefixer');
+const sassInheritance = require('gulp-sass-inheritance')
 const rename = require('gulp-rename');
+const cached = require('gulp-cached');
+const gulpif = require('gulp-if');
+const filter = require('gulp-filter');
 const fs = require('fs');
 
 const themes = ['light', 'dark', 'transp'];
@@ -24,14 +28,23 @@ const buildsGlob = './*/css/build/*.scss';
 
 // createThemedBuilds(buildDir);
 
-const build = () => gulp.src(buildsGlob)
+const build = () => gulp.src(sourcesGlob)
+  //filter out unchanged scss files, only works when watching
+  .pipe(gulpif(global.isWatching, cached('sass')))
+  //find files that depend on the files that have changed
+  .pipe(sassInheritance({dir: '.',debug: false}))
+  //filter out internal imports (folders and files starting with "_" )
+  .pipe(filter(file => !/\/_/.test(file.path) || !/^_/.test(file.relative)))
   .pipe(sourcemaps.init())
   .pipe(sass(sassOptions).on('error', sass.logError))
   .pipe(sourcemaps.write())
   .pipe(renameAs('dev'))
   .pipe(destination());
 
+const setWatching = async () => { global.isWatching = true; };
+
 gulp.task('css', gulp.series([
+  setWatching,
   build,
   () => gulp.watch(sourcesGlob, build)
 ]));
diff --git a/ui/package.json b/ui/package.json
index fa8480e25f..9844373349 100644
--- a/ui/package.json
+++ b/ui/package.json
@@ -22,9 +22,12 @@
   "private": true,
   "dependencies": {
     "gulp": "^4",
-    "gulp-uglify": "^3",
-    "gulp-size": "^3",
+    "gulp-cached": "^1.1.1",
     "gulp-concat": "^2.6",
-    "gulp-sass-inheritance": "^1.1"
+    "gulp-filter": "^5.1.0",
+    "gulp-if": "^2.0.2",
+    "gulp-sass-inheritance": "^1.1",
+    "gulp-size": "^3",
+    "gulp-uglify": "^3"
   }
 }
diff --git a/ui/yarn.lock b/ui/yarn.lock
index f2f84f91e8..8cbd219021 100644
--- a/ui/yarn.lock
+++ b/ui/yarn.lock
@@ -193,7 +193,14 @@ array-sort@^1.0.0:
     get-value "^2.0.6"
     kind-of "^5.0.2"
 
-array-uniq@^1.0.2:
+array-union@^1.0.1:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/array-union/-/array-union-1.0.2.tgz#9a34410e4f4e3da23dea375be5be70f24778ec39"
+  integrity sha1-mjRBDk9OPaI96jdb5b5w8kd47Dk=
+  dependencies:
+    array-uniq "^1.0.1"
+
+array-uniq@^1.0.1, array-uniq@^1.0.2:
   version "1.0.3"
   resolved "https://registry.yarnpkg.com/array-uniq/-/array-uniq-1.0.3.tgz#af6ac877a25cc7f74e058894753858dfdb24fdb6"
   integrity sha1-r2rId6Jcx/dOBYiUdThY39sk/bY=
@@ -208,6 +215,11 @@ array-unique@^0.3.2:
   resolved "https://registry.yarnpkg.com/array-unique/-/array-unique-0.3.2.tgz#a894b75d4bc4f6cd679ef3244a9fd8f46ae2d428"
   integrity sha1-qJS3XUvE9s1nnvMkSp/Y9Gri1Cg=
 
+arrify@^1.0.0:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/arrify/-/arrify-1.0.1.tgz#898508da2226f380df904728456849c1501a4b0d"
+  integrity sha1-iYUI2iIm84DfkEcoRWhJwVAaSw0=
+
 assign-symbols@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/assign-symbols/-/assign-symbols-1.0.0.tgz#59667f41fadd4f20ccbc2bb96b8d4f7f78ec0367"
@@ -646,7 +658,7 @@ duplexer@^0.1.1, duplexer@~0.1.1:
   resolved "https://registry.yarnpkg.com/duplexer/-/duplexer-0.1.1.tgz#ace6ff808c1ce66b57d1ebf97977acb02334cfc1"
   integrity sha1-rOb/gIwc5mtX0ev5eXessCM0z8E=
 
-duplexify@^3.2.0, duplexify@^3.6.0:
+duplexify@^3.2.0, duplexify@^3.5.0, duplexify@^3.6.0:
   version "3.7.1"
   resolved "https://registry.yarnpkg.com/duplexify/-/duplexify-3.7.1.tgz#2a4df5317f6ccfd91f86d6fd25d8d8a103b88309"
   integrity sha512-07z8uv2wMyS51kKhD1KsdXJg5WQ6t93RneqRxUHnskXVtlYYkLqM0gqStQZ3pj073g687jPCHrqNfCzawLYh5g==
@@ -916,6 +928,11 @@ for-own@^1.0.0:
   dependencies:
     for-in "^1.0.1"
 
+fork-stream@^0.0.4:
+  version "0.0.4"
+  resolved "https://registry.yarnpkg.com/fork-stream/-/fork-stream-0.0.4.tgz#db849fce77f6708a5f8f386ae533a0907b54ae70"
+  integrity sha1-24Sfznf2cIpfjzhq5TOgkHtUrnA=
+
 fragment-cache@^0.2.1:
   version "0.2.1"
   resolved "https://registry.yarnpkg.com/fragment-cache/-/fragment-cache-0.2.1.tgz#4290fad27f13e89be7f33799c6bc5a0abfff0d19"
@@ -1105,6 +1122,14 @@ graceful-fs@^4.0.0, graceful-fs@^4.1.11, graceful-fs@^4.1.2, graceful-fs@^4.1.6:
   resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.1.15.tgz#ffb703e1066e8a0eeaa4c8b80ba9253eeefbfb00"
   integrity sha512-6uHUhOPEBgQ24HM+r6b/QwWfZq+yiFcipKFrOFiBEnWdy5sdzYoi+pJeQaPI5qOLRFqWmAXUPQNsielzdLoecA==
 
+gulp-cached@^1.1.1:
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/gulp-cached/-/gulp-cached-1.1.1.tgz#fe7cd4f87f37601e6073cfedee5c2bdaf8b6acce"
+  integrity sha1-/nzU+H83YB5gc8/t7lwr2vi2rM4=
+  dependencies:
+    lodash.defaults "^4.2.0"
+    through2 "^2.0.1"
+
 gulp-cli@^2.0.0:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/gulp-cli/-/gulp-cli-2.0.1.tgz#7847e220cb3662f2be8a6d572bf14e17be5a994b"
@@ -1138,6 +1163,31 @@ gulp-concat@^2.6:
     through2 "^2.0.0"
     vinyl "^2.0.0"
 
+gulp-filter@^5.1.0:
+  version "5.1.0"
+  resolved "https://registry.yarnpkg.com/gulp-filter/-/gulp-filter-5.1.0.tgz#a05e11affb07cf7dcf41a7de1cb7b63ac3783e73"
+  integrity sha1-oF4Rr/sHz33PQafeHLe2OsN4PnM=
+  dependencies:
+    multimatch "^2.0.0"
+    plugin-error "^0.1.2"
+    streamfilter "^1.0.5"
+
+gulp-if@^2.0.2:
+  version "2.0.2"
+  resolved "https://registry.yarnpkg.com/gulp-if/-/gulp-if-2.0.2.tgz#a497b7e7573005041caa2bc8b7dda3c80444d629"
+  integrity sha1-pJe351cwBQQcqivIt92jyARE1ik=
+  dependencies:
+    gulp-match "^1.0.3"
+    ternary-stream "^2.0.1"
+    through2 "^2.0.1"
+
+gulp-match@^1.0.3:
+  version "1.0.3"
+  resolved "https://registry.yarnpkg.com/gulp-match/-/gulp-match-1.0.3.tgz#91c7c0d7f29becd6606d57d80a7f8776a87aba8e"
+  integrity sha1-kcfA1/Kb7NZgbVfYCn+Hdqh6uo4=
+  dependencies:
+    minimatch "^3.0.3"
+
 gulp-sass-inheritance@^1.1:
   version "1.1.2"
   resolved "https://registry.yarnpkg.com/gulp-sass-inheritance/-/gulp-sass-inheritance-1.1.2.tgz#4f5b2bb712d4cc6c57d0a133d55f4545eb579f92"
@@ -1739,6 +1789,11 @@ lodash._root@^3.0.0:
   resolved "https://registry.yarnpkg.com/lodash._root/-/lodash._root-3.0.1.tgz#fba1c4524c19ee9a5f8136b4609f017cf4ded692"
   integrity sha1-+6HEUkwZ7ppfgTa0YJ8BfPTe1pI=
 
+lodash.defaults@^4.2.0:
+  version "4.2.0"
+  resolved "https://registry.yarnpkg.com/lodash.defaults/-/lodash.defaults-4.2.0.tgz#d09178716ffea4dde9e5fb7b37f6f0802274580c"
+  integrity sha1-0JF4cW/+pN3p5ft7N/bwgCJ0WAw=
+
 lodash.escape@^3.0.0:
   version "3.2.0"
   resolved "https://registry.yarnpkg.com/lodash.escape/-/lodash.escape-3.2.0.tgz#995ee0dc18c1b48cc92effae71a10aab5b487698"
@@ -1899,7 +1954,7 @@ micromatch@^3.0.4, micromatch@^3.1.10, micromatch@^3.1.4:
     snapdragon "^0.8.1"
     to-regex "^3.0.2"
 
-"minimatch@2 || 3", minimatch@^3.0.4:
+"minimatch@2 || 3", minimatch@^3.0.0, minimatch@^3.0.3, minimatch@^3.0.4:
   version "3.0.4"
   resolved "https://registry.yarnpkg.com/minimatch/-/minimatch-3.0.4.tgz#5166e286457f03306064be5497e8dbb0c3d32083"
   integrity sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==
@@ -1951,6 +2006,16 @@ ms@2.0.0:
   resolved "https://registry.yarnpkg.com/ms/-/ms-2.0.0.tgz#5608aeadfc00be6c2901df5f9861788de0d597c8"
   integrity sha1-VgiurfwAvmwpAd9fmGF4jeDVl8g=
 
+multimatch@^2.0.0:
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/multimatch/-/multimatch-2.1.0.tgz#9c7906a22fb4c02919e2f5f75161b4cdbd4b2a2b"
+  integrity sha1-nHkGoi+0wCkZ4vX3UWG0zb1LKis=
+  dependencies:
+    array-differ "^1.0.0"
+    array-union "^1.0.1"
+    arrify "^1.0.0"
+    minimatch "^3.0.0"
+
 multipipe@^0.1.2:
   version "0.1.2"
   resolved "https://registry.yarnpkg.com/multipipe/-/multipipe-0.1.2.tgz#2a8f2ddf70eed564dff2d57f1e1a137d9f05078b"
@@ -2805,6 +2870,13 @@ stream-shift@^1.0.0:
   resolved "https://registry.yarnpkg.com/stream-shift/-/stream-shift-1.0.0.tgz#d5c752825e5367e786f78e18e445ea223a155952"
   integrity sha1-1cdSgl5TZ+eG944Y5EXqIjoVWVI=
 
+streamfilter@^1.0.5:
+  version "1.0.7"
+  resolved "https://registry.yarnpkg.com/streamfilter/-/streamfilter-1.0.7.tgz#ae3e64522aa5a35c061fd17f67620c7653c643c9"
+  integrity sha512-Gk6KZM+yNA1JpW0KzlZIhjo3EaBJDkYfXtYSbOwNIQ7Zd6006E6+sCFlW1NDvFG/vnXhKmw6TJJgiEQg/8lXfQ==
+  dependencies:
+    readable-stream "^2.0.2"
+
 string-width@^1.0.1, string-width@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/string-width/-/string-width-1.0.2.tgz#118bdf5b8cdc51a2a7e70d211e07e2b0b9b107d3"
@@ -2901,6 +2973,16 @@ tar@^4:
     safe-buffer "^5.1.2"
     yallist "^3.0.2"
 
+ternary-stream@^2.0.1:
+  version "2.0.1"
+  resolved "https://registry.yarnpkg.com/ternary-stream/-/ternary-stream-2.0.1.tgz#064e489b4b5bf60ba6a6b7bc7f2f5c274ecf8269"
+  integrity sha1-Bk5Im0tb9gumpre8fy9cJ07Pgmk=
+  dependencies:
+    duplexify "^3.5.0"
+    fork-stream "^0.0.4"
+    merge-stream "^1.0.0"
+    through2 "^2.0.1"
+
 through2-filter@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/through2-filter/-/through2-filter-2.0.0.tgz#60bc55a0dacb76085db1f9dae99ab43f83d622ec"
@@ -2925,7 +3007,7 @@ through2@^0.6.0:
     readable-stream ">=1.0.33-1 <1.1.0-0"
     xtend ">=4.0.0 <4.1.0-0"
 
-through2@^2.0.0, through2@^2.0.3, through2@~2.0.0:
+through2@^2.0.0, through2@^2.0.1, through2@^2.0.3, through2@~2.0.0:
   version "2.0.5"
   resolved "https://registry.yarnpkg.com/through2/-/through2-2.0.5.tgz#01c1e39eb31d07cb7d03a96a70823260b23132cd"
   integrity sha512-/mrRod8xqpA+IHSLyGCQ2s8SPHiCDEeQJSep1jqLYeEUClOFG2Qsh+4FU6G9VeqpZnGW/Su8LQGc4YKni5rYSQ==