perf: improve VNode creation performance with compiler hints (#3334)

packages/compiler-ssr/src/index.ts

@@ -35,6 +35,7 @@ export function compile(
     // apply DOM-specific parsing options
     ...parserOptions,
     ssr: true,
+    inSSR: true,
     scopeId: options.mode === 'function' ? null : options.scopeId,
     // always prefix since compiler-ssr doesn't have size concern
     prefixIdentifiers: true,

packages/compiler-ssr/src/transforms/ssrTransformComponent.ts

@@ -241,6 +241,7 @@ function createVNodeSlotBranch(
 ): ReturnStatement {
   // apply a sub-transform using vnode-based transforms.
   const rawOptions = rawOptionsMap.get(parentContext.root)!
+
   const subOptions = {
     ...rawOptions,
     // overwrite with vnode-based transforms