diff --git a/.github/workflows/check-pr-core.yaml b/.github/workflows/check-pr-core.yaml
index f26be50a1..10db1d56e 100644
--- a/.github/workflows/check-pr-core.yaml
+++ b/.github/workflows/check-pr-core.yaml
@@ -16,6 +16,13 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
+        include:
+          - os: ubuntu-latest
+            task: spekLinuxTest spekJvmTest
+          - os: macos-latest
+            task: spekMacosTest spekJvmTest
+          - os: windows-latest
+            task: spekWindowsTest spekJvmTest
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v2
@@ -31,7 +38,7 @@ jobs:
       - uses: eskatos/gradle-command-action@v1
         with:
           build-root-directory: integration-test
-          arguments: check -PexcludeIdePlugins
+          arguments: ${{ matrix.task }} -PexcludeIdePlugins -i
   runner_junit5:
     runs-on: ubuntu-latest
     steps:
diff --git a/buildSrc/build.gradle.kts b/buildSrc/build.gradle.kts
index ac3a3456a..916971c64 100644
--- a/buildSrc/build.gradle.kts
+++ b/buildSrc/build.gradle.kts
@@ -12,8 +12,8 @@ repositories {
 }
 
 dependencies {
-    api(kotlin("gradle-plugin", version = "1.4-M3"))
-    api("org.jetbrains.dokka:dokka-gradle-plugin:0.9.17")
+    api(kotlin("gradle-plugin", version = "1.4.0-rc"))
+    api("org.jetbrains.dokka:dokka-gradle-plugin:1.4.0-rc")
     api("com.jfrog.bintray.gradle:gradle-bintray-plugin:1.8.4")
     api("gradle.plugin.org.jetbrains.intellij.plugins:gradle-intellij-plugin:0.4.10")
     api("com.github.jengelman.gradle.plugins:shadow:4.0.2")
diff --git a/buildSrc/src/main/kotlin/Dependencies.kt b/buildSrc/src/main/kotlin/Dependencies.kt
index b8a89a5b5..607dff739 100644
--- a/buildSrc/src/main/kotlin/Dependencies.kt
+++ b/buildSrc/src/main/kotlin/Dependencies.kt
@@ -16,7 +16,7 @@ object Dependencies {
     val mockitoCore = "org.mockito:mockito-core:2.23.4"
     val mockitoInline = "org.mockito:mockito-inline:2.23.4"
 
-    val kotlinCoroutinesCore = "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.7-1.4-M3"
+    val kotlinCoroutinesCore = "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.8-1.4.0-rc"
 
     val autoService = "com.google.auto.service:auto-service:1.0-rc4"
 }
diff --git a/gradle.properties b/gradle.properties
index 74ce827a9..85770b678 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,2 +1,3 @@
-kotlin.mpp.enableGranularSourceSetsMetadata=true
+# This causes problems with composite builds!
+# kotlin.mpp.enableGranularSourceSetsMetadata=true
 org.gradle.jvmArgs=-Xmx3G
\ No newline at end of file
diff --git a/integration-test/build.gradle.kts b/integration-test/build.gradle.kts
index c74d6d5c9..6c216f1e2 100644
--- a/integration-test/build.gradle.kts
+++ b/integration-test/build.gradle.kts
@@ -10,38 +10,29 @@ repositories {
 }
 
 kotlin {
-  metadata {}
   jvm {}
+  js {}
   linuxX64("linux") {}
   macosX64("macos") {}
   mingwX64("windows") {}
 
   sourceSets {
-    val commonMain by getting {
-      dependencies {
-        implementation(kotlin("stdlib"))
-      }
-    }
+    val commonMain by getting
 
     val commonTest by getting {
       dependencies {
         implementation("org.spekframework.spek2:spek-dsl")
+        implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.8-1.4.0-rc")
         implementation("org.spekframework.spek2:spek-runtime")
         implementation(kotlin("test"))
       }
     }
 
     jvm {
-      compilations["main"].defaultSourceSet {
-        dependencies {
-          implementation(kotlin("stdlib-jdk8"))
-        }
-      }
-
       compilations["test"].defaultSourceSet {
         dependencies {
           runtimeOnly(kotlin("reflect"))
-          implementation("org.jetbrains.kotlinx:kotlinx-coroutines-test:1.3.7-1.4-M3")
+          implementation("org.jetbrains.kotlinx:kotlinx-coroutines-test:1.3.8-1.4.0-rc")
           implementation("com.nhaarman.mockitokotlin2:mockito-kotlin:2.0.0")
           implementation("org.mockito:mockito-core:2.23.4")
           runtimeOnly("org.spekframework.spek2:spek-runner-junit5")
@@ -112,7 +103,8 @@ spek2 {
 tasks {
   afterEvaluate {
     val runSpekJvmTest by getting(Test::class) {
-      systemProperty("spek2.discovery.concurrent", "")
+      systemProperty("spek2.discovery.parallel.enabled", "")
+      systemProperty("spek2.execution.parallel.enabled", "")
       filter {
         includeTestsMatching("org.spekframework.spek2.*")
       }
diff --git a/integration-test/buildSrc/build.gradle.kts b/integration-test/buildSrc/build.gradle.kts
index fe00d929d..3e6d70b25 100644
--- a/integration-test/buildSrc/build.gradle.kts
+++ b/integration-test/buildSrc/build.gradle.kts
@@ -5,5 +5,5 @@ repositories {
 }
 
 dependencies {
-  implementation(kotlin("gradle-plugin", version = "1.4-M3"))
+  implementation(kotlin("gradle-plugin", version = "1.4.0-rc"))
 }
\ No newline at end of file
diff --git a/integration-test/gradle.properties b/integration-test/gradle.properties
index 659b74c01..dce9c2baf 100644
--- a/integration-test/gradle.properties
+++ b/integration-test/gradle.properties
@@ -1 +1,3 @@
+# This causes problems with composite builds!
+# kotlin.mpp.enableGranularSourceSetsMetadata=true
 org.gradle.jvmargs=-Xmx3G
\ No newline at end of file
diff --git a/integration-test/settings.gradle.kts b/integration-test/settings.gradle.kts
index e711b7b04..c3110dce8 100644
--- a/integration-test/settings.gradle.kts
+++ b/integration-test/settings.gradle.kts
@@ -1,18 +1,8 @@
 includeBuild("../") {
   dependencySubstitution {
-    substitute(module("org.spekframework.spek2:spek-gradle-plugin:0.1.0")).with(project(":spek-gradle-plugin"))
+    substitute(module("org.spekframework.spek2:spek-gradle-plugin")).with(project(":spek-gradle-plugin"))
     substitute(module("org.spekframework.spek2:spek-dsl")).with(project(":spek-dsl"))
-    substitute(module("org.spekframework.spek2:spek-dsl-metadata")).with(project(":spek-dsl"))
-    substitute(module("org.spekframework.spek2:spek-dsl-jvm")).with(project(":spek-dsl"))
-    substitute(module("org.spekframework.spek2:spek-dsl-linux")).with(project(":spek-dsl"))
-    substitute(module("org.spekframework.spek2:spek-dsl-windows")).with(project(":spek-dsl"))
-    substitute(module("org.spekframework.spek2:spek-dsl-macos")).with(project(":spek-dsl"))
     substitute(module("org.spekframework.spek2:spek-runtime")).with(project(":spek-runtime"))
-    substitute(module("org.spekframework.spek2:spek-runtime-metadata")).with(project(":spek-runtime"))
-    substitute(module("org.spekframework.spek2:spek-runtime-jvm")).with(project(":spek-runtime"))
-    substitute(module("org.spekframework.spek2:spek-runtime-linux")).with(project(":spek-runtime"))
-    substitute(module("org.spekframework.spek2:spek-runtime-windows")).with(project(":spek-runtime"))
-    substitute(module("org.spekframework.spek2:spek-runtime-macos")).with(project(":spek-runtime"))
     substitute(module("org.spekframework.spek2:spek-runner-junit5")).with(project(":spek-runner-junit5"))
     substitute(module("org.spekframework.spek2:spek-kotlin-compiler-plugin-jvm")).with(project(":spek-kotlin-compiler-plugin-jvm"))
     substitute(module("org.spekframework.spek2:spek-kotlin-compiler-plugin-native")).with(project(":spek-kotlin-compiler-plugin-native"))
diff --git a/integration-test/src/commonTest/kotlin/org/spekframework/spek2/TestSupport.kt b/integration-test/src/commonTest/kotlin/org/spekframework/spek2/TestSupport.kt
index 8780073cf..8cbc6be01 100644
--- a/integration-test/src/commonTest/kotlin/org/spekframework/spek2/TestSupport.kt
+++ b/integration-test/src/commonTest/kotlin/org/spekframework/spek2/TestSupport.kt
@@ -121,7 +121,7 @@ class SpekTestHelper {
         val runtime = SpekRuntime()
         val recorder = ExecutionRecorder()
 
-        val discoveryResult = runtime.discover(DiscoveryRequest(context, listOf(*paths)))
+        val discoveryResult = runtime.discoverAsync(DiscoveryRequest(context, listOf(*paths)))
         runtime.executeAsync(ExecutionRequest(discoveryResult.roots, recorder))
 
         return recorder
diff --git a/spek-dsl/build.gradle.kts b/spek-dsl/build.gradle.kts
index bf0cf9899..15f10f33c 100644
--- a/spek-dsl/build.gradle.kts
+++ b/spek-dsl/build.gradle.kts
@@ -69,27 +69,6 @@ kotlin {
       }
     }
   }
-
-  sourceSets {
-    val commonMain by getting {
-      dependencies {
-        implementation(kotlin("stdlib-common"))
-        api(Dependencies.kotlinCoroutinesCore)
-      }
-    }
-
-    val jvmMain by getting {
-      dependencies {
-        implementation(kotlin("stdlib-jdk8"))
-      }
-    }
-
-    val jsMain by getting {
-      dependencies {
-        implementation(kotlin("stdlib-js"))
-      }
-    }
-  }
 }
 
 val stubJavaDocJar by tasks.registering(Jar::class) {
diff --git a/spek-runtime/build.gradle.kts b/spek-runtime/build.gradle.kts
index 407db779f..55061f5f0 100644
--- a/spek-runtime/build.gradle.kts
+++ b/spek-runtime/build.gradle.kts
@@ -27,6 +27,17 @@ kotlin {
 
     }
 
+    js {
+        mavenPublication {
+            groupId = "org.spekframework.spek2"
+            artifactId = "spek-runtime-js"
+            pom {
+                name.set("Spek Runtime JS")
+                description.set("Kotlin JS module for spek-runtime")
+            }
+        }
+    }
+
     linuxX64("linux") {
         mavenPublication {
             groupId = "org.spekframework.spek2"
@@ -64,7 +75,6 @@ kotlin {
         val commonMain by getting {
             dependencies {
                 api(project(":spek-dsl"))
-                implementation(kotlin("stdlib-common"))
                 implementation(Dependencies.kotlinCoroutinesCore)
             }
         }
@@ -72,7 +82,6 @@ kotlin {
         jvm {
             compilations["main"].defaultSourceSet {
                 dependencies {
-                    implementation(kotlin("stdlib-jdk8"))
                     implementation(kotlin("reflect"))
                     implementation(Dependencies.classgraph)
                 }
diff --git a/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/Executor.kt b/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/Executor.kt
index df125286d..379000cd0 100644
--- a/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/Executor.kt
+++ b/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/Executor.kt
@@ -1,7 +1,6 @@
 package org.spekframework.spek2.runtime
 
 import kotlinx.coroutines.*
-import kotlinx.coroutines.withTimeoutOrNull
 import org.spekframework.spek2.dsl.Skip
 import org.spekframework.spek2.runtime.execution.ExecutionListener
 import org.spekframework.spek2.runtime.execution.ExecutionRequest
@@ -15,7 +14,17 @@ import kotlin.coroutines.EmptyCoroutineContext
 class Executor {
     suspend fun execute(request: ExecutionRequest) {
         request.executionListener.executionStart()
-        request.roots.forEach { execute(it, request.executionListener) }
+        // note that this call will be run in parallel depending on the CoroutineDispatcher used
+        supervisorScope {
+            request.roots.map { async { execute(it, request.executionListener) } }
+                .forEach { job ->
+                    try {
+                        job.await()
+                    } catch (e: Throwable) {
+                        e.printStackTrace()
+                    }
+                }
+        }
         request.executionListener.executionFinish()
     }
 
diff --git a/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/SpekRuntime.kt b/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/SpekRuntime.kt
index 0229cd61d..0055aad80 100644
--- a/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/SpekRuntime.kt
+++ b/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/SpekRuntime.kt
@@ -41,31 +41,39 @@ class SpekRuntime {
         }
     }
 
+    suspend fun discoverAsync(discoveryRequest: DiscoveryRequest): DiscoveryResult {
+        val scopes = mutableListOf<GroupScopeImpl>()
+        coroutineScope {
+            filterScopes(discoveryRequest).collect { scope ->
+                scopes.add(scope)
+            }
+        }
+
+        return DiscoveryResult(scopes)
+    }
+
     @OptIn(ExperimentalTime::class)
     fun discover(discoveryRequest: DiscoveryRequest): DiscoveryResult {
-        val scopes = mutableListOf<GroupScopeImpl>()
-        println("Spek discovery started.")
+        lateinit var results: DiscoveryResult
+        println("spek2: Discovery started.")
         val time = measureTime {
             doRunBlocking {
-                if (isConcurrentDiscoveryEnabled(false)) {
+                if (isParallelDiscoveryEnabled(false)) {
+                    println("spek2: Running discovery phase in parallel.")
                     withContext(Dispatchers.Default) {
-                        filterScopes(discoveryRequest).collect { scope ->
-                            scopes.add(scope)
-                        }
+                        results = discoverAsync(discoveryRequest)
                     }
                 } else {
-                    filterScopes(discoveryRequest).collect { scope ->
-                        scopes.add(scope)
-                    }
+                    results = discoverAsync(discoveryRequest)
                 }
             }
         }
 
-        println("Spek discovery completed in ${time.inMilliseconds} ms")
-        return DiscoveryResult(scopes)
+        println("spek2: Discovery completed in ${time.inMilliseconds} ms")
+        return results
     }
 
-
+    // For internal use only!
     suspend fun executeAsync(request: ExecutionRequest) {
         Executor().execute(request)
     }
@@ -74,9 +82,16 @@ class SpekRuntime {
     fun execute(request: ExecutionRequest) {
         doRunBlocking {
             val job = coroutineScope {
-                // inherit the dispatcher from doRunBlocking (which is an event loop backed by the main thread)
-                launch {
-                    executeAsync(request)
+                if (isParallelExecutionEnabled(false)) {
+                    println("spek2: Running execution phase in parallel.")
+                    launch(Dispatchers.Default) {
+                        executeAsync(request)
+                    }
+                } else {
+                    // inherit the dispatcher from doRunBlocking (which is an event loop backed by the main thread)
+                    launch {
+                        executeAsync(request)
+                    }
                 }
             }
 
@@ -121,5 +136,6 @@ class SpekRuntime {
     }
 }
 
-expect fun isConcurrentDiscoveryEnabled(default: Boolean): Boolean
+expect fun isParallelDiscoveryEnabled(default: Boolean): Boolean
+expect fun isParallelExecutionEnabled(default: Boolean): Boolean
 expect fun getGlobalTimeoutSetting(default: Long): Long
\ No newline at end of file
diff --git a/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/JvmDiscoveryContextFactory.kt b/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/JvmDiscoveryContextFactory.kt
index 958dfda78..c808dcf1b 100644
--- a/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/JvmDiscoveryContextFactory.kt
+++ b/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/JvmDiscoveryContextFactory.kt
@@ -10,7 +10,6 @@ import org.spekframework.spek2.runtime.discovery.DiscoveryContext
 import kotlin.reflect.KClass
 import kotlin.reflect.full.findAnnotation
 import kotlin.reflect.full.primaryConstructor
-import kotlin.streams.toList
 
 object JvmDiscoveryContextFactory {
     // classgraph scan is already done in parallel, this property allows it to be overriden
@@ -50,7 +49,6 @@ object JvmDiscoveryContextFactory {
             .enableClassInfo()
             // any jar on the classpath won't be scanned
             .disableJarScanning()
-            .verbose()
 
         if (testDirs.isNotEmpty()) {
             cg.overrideClasspath(System.getProperty("java.class.path"), *testDirs.toTypedArray())
@@ -66,7 +64,7 @@ object JvmDiscoveryContextFactory {
     }
 
     private fun filterScanResult(scanResult: ScanResult) : List<KClass<out Spek>> {
-        return scanResult.getSubclasses(Spek::class.qualifiedName!!).stream()
+        return scanResult.getSubclasses(Spek::class.qualifiedName!!)
             .map { it.loadClass() as Class<out Spek> }
             .filter { !it.isAnonymousClass }
             .map { it.kotlin }
diff --git a/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/timeout.kt b/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/timeout.kt
index 50c23ba93..15ce5bc06 100644
--- a/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/timeout.kt
+++ b/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/timeout.kt
@@ -1,13 +1,14 @@
 package org.spekframework.spek2.runtime
 
 actual fun getGlobalTimeoutSetting(default: Long): Long {
-    var override = System.getProperty("SPEK_TIMEOUT")?.toLong()
-    if (override == null) {
-        override = System.getProperty("spek2.timeout")?.toLong()
-    }
+    var override = System.getProperty("spek2.execution.test.timeout")?.toLong()
     return override ?: default
 }
 
-actual fun isConcurrentDiscoveryEnabled(default: Boolean): Boolean {
-    return System.getProperty("spek2.discovery.concurrent") != null || default
+actual fun isParallelDiscoveryEnabled(default: Boolean): Boolean {
+    return System.getProperty("spek2.discovery.parallel.enabled") != null || default
+}
+
+actual fun isParallelExecutionEnabled(default: Boolean): Boolean {
+    return System.getProperty("spek2.execution.parallel.enabled") != null || default
 }
\ No newline at end of file
diff --git a/spek-runtime/src/nativeMain/kotlin/org/spekframework/spek2/runtime/timeout.kt b/spek-runtime/src/nativeMain/kotlin/org/spekframework/spek2/runtime/timeout.kt
index 08a97ce53..ee63124c7 100644
--- a/spek-runtime/src/nativeMain/kotlin/org/spekframework/spek2/runtime/timeout.kt
+++ b/spek-runtime/src/nativeMain/kotlin/org/spekframework/spek2/runtime/timeout.kt
@@ -4,6 +4,10 @@ actual fun getGlobalTimeoutSetting(default: Long): Long {
     return default
 }
 
-actual fun isConcurrentDiscoveryEnabled(default: Boolean): Boolean {
+actual fun isParallelDiscoveryEnabled(default: Boolean): Boolean {
+    return default
+}
+
+actual fun isParallelExecutionEnabled(default: Boolean): Boolean {
     return default
 }
\ No newline at end of file