diff --git a/lib/index.js b/lib/index.js
index 4ae18d0..bad6a1c 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -26,7 +26,8 @@ _.extend(config.engine, {
     customIntentTypes: {},
     historyChunkSize: 20,
     useSigintTimeout: false,
-    reportMemoryUsageInterval: 0
+    reportMemoryUsageInterval: 0,
+    enableInspector: false,
 });
 
 config.engine.on('playerSandbox', (sandbox) => {
@@ -508,4 +509,4 @@ exports.queue = queue;
 
 exports.constants = config.common.constants;
 
-process.on('disconnect', () => process.exit());
\ No newline at end of file
+process.on('disconnect', () => process.exit());
diff --git a/lib/runtime/make.js b/lib/runtime/make.js
index 1a2739a..ef407be 100644
--- a/lib/runtime/make.js
+++ b/lib/runtime/make.js
@@ -315,7 +315,7 @@ module.exports = function(userId, onlyInRoom) {
             runtimeUserVm.clear(userId);
             console.error('isolated-vm timeout', userId);
             pubsub.publish(`user:${userId}/cpu`, JSON.stringify({cpu: 'error'}));
-        }, 5000);
+        }, Math.max(5000, config.engine.mainLoopResetInterval));
         make(scope, userId, onlyInRoom).then(resolve).catch(reject);
     })
         .then(result => {
diff --git a/lib/runtime/user-vm.js b/lib/runtime/user-vm.js
index 0659112..2860e17 100644
--- a/lib/runtime/user-vm.js
+++ b/lib/runtime/user-vm.js
@@ -18,60 +18,67 @@ exports.create = async function({userId, staticTerrainData, staticTerrainDataSiz
             exports.clear(userId);
             throw 'Script execution has been terminated: your isolate disposed unexpectedly, restarting virtual machine';
         }
-        if(codeTimestamp > vms[userId].codeTimestamp) {
+        if(!vms[userId].ready) {
+            return vms[userId].promise;
+        } else if(codeTimestamp > vms[userId].codeTimestamp) {
             exports.clear(userId);
         }
     }
 
     if(!vms[userId]) {
-        let isolate = new ivm.Isolate({snapshot, memoryLimit: 256 + staticTerrainDataSize/1024/1024});
-        let context = await isolate.createContext();
-        let [ nativeModInstance, initScript, cleanupScript ] = await Promise.all([
-            nativeMod.create(context),
-            isolate.compileScript('_init();'),
-            isolate.compileScript('new ' + function () {
-                delete global._ivm;
-                delete global._isolate;
-                delete global._context;
-                delete global._init;
-                delete global._evalFn;
-                delete global._start;
-                delete global._setStaticTerrainData;
-                delete global._worldSize;
-                delete global._nativeMod;
-            }),
-        ]);
-        await Promise.all([
-            context.global.set('global', context.global.derefInto()),
-            context.global.set('_ivm', ivm),
-            context.global.set('_isolate', isolate),
-            context.global.set('_context', context),
-            context.global.set('_worldSize', index.getWorldSize()),
-            context.global.set('_nativeMod', nativeModInstance.derefInto()),
-            initScript.run(context),
-        ]);
-        let [ evalFn, start, setStaticTerrainData ] = await Promise.all([
-            context.global.get('_evalFn'),
-            context.global.get('_start'),
-            context.global.get('_setStaticTerrainData'),
-        ]);
+        let inspector = config.engine.enableInspector;
+        let isolate = new ivm.Isolate({inspector, snapshot, memoryLimit: 256 + staticTerrainDataSize/1024/1024});
+        let vm = vms[userId] = {isolate, ready: false};
+        vm.promise = async function() {
+            let context = await isolate.createContext({inspector});
+            let [ nativeModInstance, initScript, cleanupScript ] = await Promise.all([
+                nativeMod.create(context),
+                isolate.compileScript('_init();'),
+                isolate.compileScript('new ' + function () {
+                    delete global._ivm;
+                    delete global._isolate;
+                    delete global._context;
+                    delete global._init;
+                    delete global._evalFn;
+                    delete global._start;
+                    delete global._setStaticTerrainData;
+                    delete global._worldSize;
+                    delete global._nativeMod;
+                }),
+            ]);
+            await Promise.all([
+                context.global.set('global', context.global.derefInto()),
+                context.global.set('_ivm', ivm),
+                context.global.set('_isolate', isolate),
+                context.global.set('_context', context),
+                context.global.set('_worldSize', index.getWorldSize()),
+                context.global.set('_nativeMod', nativeModInstance.derefInto()),
+                initScript.run(context),
+            ]);
+            let [ evalFn, start, setStaticTerrainData ] = await Promise.all([
+                context.global.get('_evalFn'),
+                context.global.get('_start'),
+                context.global.get('_setStaticTerrainData'),
+            ]);
 
-        await Promise.all([
-            setStaticTerrainData.apply(undefined, [
-                new ivm.ExternalCopy(staticTerrainData.buffer).copyInto({ release: true }),
-                new ivm.ExternalCopy(staticTerrainData.roomOffsets).copyInto({ release: true }),
-            ]),
-            cleanupScript.run(context),
-        ]);
+            await Promise.all([
+                setStaticTerrainData.apply(undefined, [
+                    new ivm.ExternalCopy(staticTerrainData.buffer).copyInto({ release: true }),
+                    new ivm.ExternalCopy(staticTerrainData.roomOffsets).copyInto({ release: true }),
+                ]),
+                cleanupScript.run(context),
+            ]);
 
-        vms[userId] = {
-            isolate,
-            context,
-            start,
-            evalFn,
-            nativeModInstance,
-            codeTimestamp
-        };
+            Object.assign(vm, {
+                ready: true,
+                context,
+                start,
+                evalFn,
+                nativeModInstance,
+                codeTimestamp
+            });
+        }();
+        await vm.promise;
     }
 
     vms[userId].lastUsed = Date.now();
@@ -79,16 +86,15 @@ exports.create = async function({userId, staticTerrainData, staticTerrainDataSiz
 
 exports.get = function(userId) {
     userId = ""+userId;
-    return vms[userId];
+    let vm = vms[userId];
+    if (vm && vm.ready) {
+        return vm;
+    }
 };
 exports.clear = function(userId) {
     userId = ""+userId;
     if(vms[userId]) {
         try {
-            vms[userId].start.dispose();
-            vms[userId].evalFn.dispose();
-            vms[userId].nativeModInstance.dispose();
-            vms[userId].context.release();
             if(!vms[userId].isolate.isDisposed) {
                 vms[userId].isolate.dispose();
             }