diff --git a/.gitmodules b/.gitmodules
index efca0b4ec52e..427e2f0709b3 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -44,3 +44,7 @@
 	path = public/vendor/Sunsetter8
 	url = https://github.com/niklasf/Sunsetter8
 	branch = js
+[submodule "public/vendor/stockfish.pexe"]
+	path = public/vendor/stockfish.pexe
+	url = https://github.com/niklasf/stockfish.pexe
+	branch = ddugovic
diff --git a/public/vendor/stockfish.pexe b/public/vendor/stockfish.pexe
new file mode 160000
index 000000000000..6e07387f0ade
--- /dev/null
+++ b/public/vendor/stockfish.pexe
@@ -0,0 +1 @@
+Subproject commit 6e07387f0adef9d521dd2eb4b1400031d4591e14
diff --git a/ui/analyse/src/ceval/cevalCtrl.js b/ui/analyse/src/ceval/cevalCtrl.js
index 7cf2b224eaae..5b14ada9f91b 100644
--- a/ui/analyse/src/ceval/cevalCtrl.js
+++ b/ui/analyse/src/ceval/cevalCtrl.js
@@ -2,8 +2,8 @@ var m = require('mithril');
 var makePool = require('./cevalPool');
 var dict = require('./cevalDict');
 var util = require('../util');
-var stockfishWorker = require('./stockfishWorker');
-var sunsetterWorker = require('./sunsetterWorker');
+var stockfishProtocol = require('./stockfishProtocol');
+var sunsetterProtocol = require('./sunsetterProtocol');
 
 module.exports = function(possible, variant, emit) {
 
@@ -16,13 +16,22 @@ module.exports = function(possible, variant, emit) {
   var allowed = m.prop(true);
   var enabled = m.prop(possible() && allowed() && lichess.storage.get(storageKey) === '1');
   var started = false;
-  var engine = variant.key !== 'crazyhouse' ? stockfishWorker : sunsetterWorker;
 
-  var pool = makePool({
-    minDepth: minDepth,
-    maxDepth: maxDepth,
-    variant: variant
-  }, engine, nbWorkers);
+  var pool;
+  if (variant.key !== 'crazyhouse') {
+    pool = makePool(stockfishProtocol, {
+      asmjs: '/assets/vendor/stockfish.js/stockfish.js',
+      pnacl: '/assets/vendor/stockfish.pexe/nacl/stockfish.nmf'
+    }, {
+      minDepth: minDepth,
+      maxDepth: maxDepth,
+      variant: variant,
+    });
+  } else {
+    pool = makePool(sunsetterProtocol, {
+      asmjs: '/assets/vendor/Sunsetter8/sunsetter.js'
+    });
+  }
 
   // adjusts maxDepth based on nodes per second
   var npsRecorder = (function() {
diff --git a/ui/analyse/src/ceval/cevalPool.js b/ui/analyse/src/ceval/cevalPool.js
index fbaf486b1878..eaa8bc677d2c 100644
--- a/ui/analyse/src/ceval/cevalPool.js
+++ b/ui/analyse/src/ceval/cevalPool.js
@@ -1,7 +1,65 @@
 var m = require('mithril');
 
-module.exports = function(opts, makeWorker, nb) {
+function makeHelper(makeWorker, terminateWorker, poolOpts, makeProtocol, protocolOpts) {
+  var worker, protocol, api;
 
+  var boot = function () {
+    worker = makeWorker(poolOpts);
+    protocol = makeProtocol(api, protocolOpts);
+    worker.addEventListener('message', function(e) {
+      protocol.received(e.data);
+    }, true);
+  };
+
+  var stop = function() {
+    var stopped = m.deferred(false);
+    setTimeout(function () {
+      stopped.reject();
+    }, 1000);
+    return protocol.stop(stopped);
+  };
+
+  api = {
+    send: function(text) {
+      worker.postMessage(text);
+    },
+    start: function (work) {
+      stop().then(function () {
+        protocol.start(work);
+      }, function () {
+        terminateWorker(worker);
+        boot();
+      });
+    },
+    stop: stop
+  };
+
+  boot();
+
+  return api;
+}
+
+function makeWebWorker(makeProtocol, poolOpts, protocolOpts) {
+  return makeHelper(function () {
+    return new Worker(poolOpts.asmjs);
+  }, function (worker) {
+    worker.terminate();
+  }, poolOpts, makeProtocol, protocolOpts);
+}
+
+function makePNaClModule(makeProtocol, poolOpts, protocolOpts) {
+  return makeHelper(function () {
+    var module = document.createElement('embed');
+    module.setAttribute('src', poolOpts.pnacl);
+    module.setAttribute('type', 'application/x-pnacl');
+    module.setAttribute('width', '0');
+    module.setAttribute('height', '0');
+    document.body.appendChild(module);
+    return module;
+  }, function () {}, poolOpts, makeProtocol, protocolOpts);
+}
+
+module.exports = function(makeProtocol, poolOpts, protocolOpts) {
   var workers = [];
   var token = -1;
 
@@ -12,9 +70,13 @@ module.exports = function(opts, makeWorker, nb) {
   };
 
   var initWorkers = function() {
-    if (!workers.length)
-      for (var i = 1; i <= nb; i++)
-        workers.push(makeWorker(opts, 'W' + i));
+    if (workers.length) return;
+
+    if (poolOpts.pnacl && navigator.mimeTypes['application/x-pnacl'])
+      workers.push(makePNaClModule(makeProtocol, poolOpts, protocolOpts));
+    else
+      for (var i = 1; i <= 4; i++)
+        workers.push(makeWebWorker(makeProtocol, poolOpts, protocolOpts));
   }
 
   var stopAll = function() {
diff --git a/ui/analyse/src/ceval/stockfishProtocol.js b/ui/analyse/src/ceval/stockfishProtocol.js
new file mode 100644
index 000000000000..4888fc8b97bf
--- /dev/null
+++ b/ui/analyse/src/ceval/stockfishProtocol.js
@@ -0,0 +1,75 @@
+var m = require('mithril');
+
+var legacyVariantMap = {
+  fromPosition: 'Chess960',
+  chess960: 'Chess960',
+  atomic: 'Atomic',
+  horde: 'Horde',
+  crazyhouse: 'House',
+  kingOfTheHill: 'KingOfTheHill',
+  racingKings: 'Race',
+  threeCheck: '3Check',
+  antichess: 'Anti'
+};
+
+module.exports = function(worker, opts) {
+
+  var work = null;
+  var stopped = m.deferred();
+
+  var legacyVariant = legacyVariantMap[opts.variant.key];
+  if (legacyVariant) worker.send('setoption name UCI_' + legacyVariant + ' value true');
+  else worker.send('uci');
+
+  // TODO: Modern variant selector
+
+  var processOutput = function(text) {
+    if (text.indexOf('bestmove ') === 0) {
+      stopped.resolve(true);
+      return;
+    }
+    if (!work) return;
+    if (/currmovenumber|lowerbound|upperbound/.test(text)) return;
+    var matches = text.match(/depth (\d+) .*score (cp|mate) ([-\d]+) .*nps (\d+) .*pv (.+)/);
+    if (!matches) return;
+    var depth = parseInt(matches[1]);
+    if (depth < opts.minDepth) return;
+    var cp, mate;
+    if (matches[2] === 'cp') cp = parseFloat(matches[3]);
+    else mate = parseFloat(matches[3]);
+    if (work.ply % 2 === 1) {
+      if (matches[2] === 'cp') cp = -cp;
+      else mate = -mate;
+    }
+    var best = matches[5].split(' ')[0];
+    work.emit({
+      work: work,
+      eval: {
+        depth: depth,
+        cp: cp,
+        mate: mate,
+        best: best,
+        nps: parseInt(matches[4])
+      },
+      name: name
+    });
+  };
+
+  return {
+    start: function(w) {
+      work = w;
+      worker.send(['position', 'fen', work.initialFen, 'moves'].concat(work.moves).join(' '));
+      worker.send('go depth ' + work.maxDepth);
+    },
+    stop: function(s) {
+      if (!work) s.resolve(true);
+      else {
+        work = null;
+        stopped = s;
+        worker.send('stop');
+      }
+      return s.promise;
+    },
+    received: processOutput
+  };
+};
diff --git a/ui/analyse/src/ceval/stockfishWorker.js b/ui/analyse/src/ceval/stockfishWorker.js
deleted file mode 100644
index 988e95c894f9..000000000000
--- a/ui/analyse/src/ceval/stockfishWorker.js
+++ /dev/null
@@ -1,86 +0,0 @@
-var m = require('mithril');
-
-var variantMap = {
-  fromPosition: 'Chess960',
-  chess960: 'Chess960',
-  atomic: 'Atomic',
-  horde: 'Horde',
-  crazyhouse: 'House',
-  kingOfTheHill: 'KingOfTheHill',
-  racingKings: 'Race',
-  threeCheck: '3Check',
-  antichess: 'Anti'
-};
-
-module.exports = function(opts, name) {
-
-  var instance = null;
-  var busy = false;
-  var stopping = false;
-
-  var send = function(text) {
-    instance.postMessage(text);
-  };
-
-  var processOutput = function(text, work) {
-    if (text.indexOf('bestmove ') === 0) {
-      busy = false;
-      stopping = false;
-      return;
-    }
-    if (stopping) return;
-    if (/currmovenumber|lowerbound|upperbound/.test(text)) return;
-    var matches = text.match(/depth (\d+) .*score (cp|mate) ([-\d]+) .*nps (\d+) .*pv (.+)/);
-    if (!matches) return;
-    var depth = parseInt(matches[1]);
-    if (depth < opts.minDepth) return;
-    var cp, mate;
-    if (matches[2] === 'cp') cp = parseFloat(matches[3]);
-    else mate = parseFloat(matches[3]);
-    if (work.ply % 2 === 1) {
-      if (matches[2] === 'cp') cp = -cp;
-      else mate = -mate;
-    }
-    var best = matches[5].split(' ')[0];
-    work.emit({
-      work: work,
-      eval: {
-        depth: depth,
-        cp: cp,
-        mate: mate,
-        best: best,
-        nps: parseInt(matches[4])
-      },
-      name: name
-    });
-  };
-
-  var reboot = function() {
-    if (instance) instance.terminate();
-    instance = new Worker('/assets/vendor/stockfish.js/stockfish.js');
-    busy = false;
-    stopping = false;
-    var uciVariant = variantMap[opts.variant.key];
-    if (uciVariant) send('setoption name UCI_' + uciVariant + ' value true');
-    else send('uci'); // send something to warm up
-  };
-
-  reboot();
-
-  return {
-    start: function(work) {
-      if (busy) reboot();
-      busy = true;
-      send(['position', 'fen', work.initialFen, 'moves'].concat(work.moves).join(' '));
-      send('go depth ' + work.maxDepth);
-      instance.onmessage = function(msg) {
-        processOutput(msg.data, work);
-      };
-    },
-    stop: function() {
-      if (!busy) return;
-      stopping = true;
-      send('stop');
-    }
-  };
-};
diff --git a/ui/analyse/src/ceval/sunsetterWorker.js b/ui/analyse/src/ceval/sunsetterProtocol.js
similarity index 60%
rename from ui/analyse/src/ceval/sunsetterWorker.js
rename to ui/analyse/src/ceval/sunsetterProtocol.js
index a92bae0b52cc..2eeb0ad38749 100644
--- a/ui/analyse/src/ceval/sunsetterWorker.js
+++ b/ui/analyse/src/ceval/sunsetterProtocol.js
@@ -1,10 +1,11 @@
 var m = require('mithril');
 
-module.exports = function(opts, name) {
+module.exports = function(worker, opts) {
 
-  var instance = null;
-  var busy = false;
-  var stopping = false;
+  var work = null;
+  var stopped = m.deferred();
+
+  worker.send('xboard');
 
   // Sunsetter always plays only moves right away. Count the number of played
   // moves to show the correct mate in #n.
@@ -13,24 +14,19 @@ module.exports = function(opts, name) {
   var aiMoves = 0;
   var best;
 
-  var send = function(text) {
-    instance.postMessage(text);
-  };
-
-  var processOutput = function(text, work) {
+  var processOutput = function(text) {
     if (text === 'tellics stopped') {
-      busy = false;
-      stopping = false;
       aiMoves = 0;
       best = undefined;
+      stopped.resolve(true);
       return;
     }
-    if (stopping) return;
+    if (!work) return;
 
     if (text.indexOf('move ') == 0) {
       aiMoves++;
       best = text.split(' ')[1];
-      if (!stopping) send('analyze');
+      if (work) worker.send('analyze');
       return;
     }
 
@@ -42,14 +38,13 @@ module.exports = function(opts, name) {
       cp = parseInt(matches[2], 10);
       if (!aiMoves) {
         best = matches[5];
-        if (depth < opts.minDepth) return;
       }
     } else {
       matches = text.match(/Found move:\s+([a-h1-8=@PNBRQK]+)\s+([-+]?\d+)\s.*/);
       if (matches) {
         cp = parseInt(matches[2], 10);
         if (!aiMoves) best = matches[1];
-        if (!stopping) send('analyze');
+        if (work) worker.send('analyze');
       } else {
         return;
       }
@@ -81,40 +76,30 @@ module.exports = function(opts, name) {
     });
   };
 
-  var reboot = function() {
-    if (instance) instance.terminate();
-    instance = new Worker('/assets/vendor/Sunsetter8/sunsetter.js');
-    busy = false;
-    stopping = false;
-    aiMoves = 0;
-    send('xboard');
-  };
-
-  reboot();
-
   return {
-    start: function(work) {
-      if (busy) reboot();
-      busy = true;
-      send('reset ' + opts.variant.key);
-      send('setboard ' + work.initialFen);
-      send('easy');
-      send('force');
+    start: function(w) {
+      work = w;
+      worker.send('reset crazyhouse');
+      worker.send('setboard ' + work.initialFen);
+      worker.send('easy');
+      worker.send('force');
       for (var i = 0; i < work.moves.length; i++) {
-        send(work.moves[i]);
+        worker.send(work.moves[i]);
       }
-      send('go');
-      instance.onmessage = function(msg) {
-        processOutput(msg.data, work);
-      };
+      worker.send('go');
     },
-    stop: function() {
-      if (!busy) return;
-      stopping = true;
-      aiMoves = 0;
-      best = undefined;
-      send('exit');
-      send('tellics stopped');
-    }
+    stop: function(s) {
+      if (!work) s.resolve(true);
+      else {
+        stopped = s;
+        work = null;
+        aiMoves = 0;
+        best = undefined;
+        worker.send('exit');
+        worker.send('tellics stopped');
+      }
+      return s.promise;
+    },
+    received: processOutput
   };
 };