wip: disable time-slicing in compat mode

packages/runtime-core/src/createRenderer.ts

@@ -271,7 +271,40 @@ export function createRenderer(options: RendererOptions) {
     const doMount = () => {
       handle.runner = autorun(
         () => {
-          if (handle.prevTree) {
+          if (!handle.prevTree) {
+            // initial mount
+            if (__DEV__) {
+              pushWarningContext(vnode)
+            }
+            const subTree = (handle.prevTree = vnode.children = renderFunctionalRoot(
+              vnode
+            ))
+            queuePostCommitHook(() => {
+              vnode.el = subTree.el as RenderNode
+            })
+            mount(subTree, container, vnode as MountedVNode, isSVG, endNode)
+            if (__DEV__) {
+              popWarningContext()
+            }
+          } else {
+            updateFunctionalComponent(handle, isSVG)
+          }
+        },
+        {
+          scheduler: queueUpdate
+        }
+      )
+    }
+
+    // we are using vnode.ref to store the functional component's update job
+    if (__COMPAT__) {
+      doMount()
+    } else {
+      queueJob(doMount)
+    }
+  }
+
+  function updateFunctionalComponent(handle: FunctionalHandle, isSVG: boolean) {
     // mounted
     const { prevTree, current } = handle
     if (__DEV__) {
@@ -293,35 +326,6 @@ export function createRenderer(options: RendererOptions) {
     if (__DEV__) {
       popWarningContext()
     }
-          } else {
-            // initial mount
-            if (__DEV__) {
-              pushWarningContext(vnode)
-            }
-            const subTree = (handle.prevTree = vnode.children = renderFunctionalRoot(
-              vnode
-            ))
-            queuePostCommitHook(() => {
-              vnode.el = subTree.el as RenderNode
-            })
-            mount(subTree, container, vnode as MountedVNode, isSVG, endNode)
-            if (__DEV__) {
-              popWarningContext()
-            }
-          }
-        },
-        {
-          scheduler: queueUpdate
-        }
-      )
-    }
-
-    // we are using vnode.ref to store the functional component's update job
-    if (__COMPAT__) {
-      doMount()
-    } else {
-      queueJob(doMount)
-    }
   }
 
   function mountText(

packages/scheduler/src/experimental.ts

@@ -32,7 +32,7 @@ function flushAfterMicroTask() {
 }
 
 // Macrotask for time slicing
-const key = `__vueSchedulerTick`
+const key = `$vueTick`
 
 window.addEventListener(
   'message',
@@ -127,11 +127,13 @@ function flush(): void {
     } else {
       break
     }
+    if (!__COMPAT__) {
       const now = getNow()
       if (now - start > frameBudget && job.expiration > now) {
         break
       }
     }
+  }
 
   if (patchQueue.length === 0) {
     // all done, time to commit!
@@ -147,7 +149,7 @@ function flush(): void {
     }
     // some post commit hook triggered more updates...
     if (patchQueue.length > 0) {
-      if (getNow() - start > frameBudget) {
+      if (!__COMPAT__ && getNow() - start > frameBudget) {
         return flushAfterMacroTask()
       } else {
         // not out of budget yet, flush sync
@@ -162,6 +164,8 @@ function flush(): void {
     }
   } else {
     // got more job to do
+    // shouldn't reach here in compat mode, because the patchQueue is
+    // guarunteed to be drained
     flushAfterMacroTask()
   }
 }