diff --git a/packages/compiler-sfc/src/compileScript.ts b/packages/compiler-sfc/src/compileScript.ts
index 5825aa032..eb3b2d119 100644
--- a/packages/compiler-sfc/src/compileScript.ts
+++ b/packages/compiler-sfc/src/compileScript.ts
@@ -984,7 +984,7 @@ export function compileScript(
     ctx.s.prependLeft(
       startOffset,
       `\n${genDefaultAs} /*@__PURE__*/${ctx.helper(
-        vapor ? `defineVaporComponent` : `defineComponent`,
+        vapor && !ssr ? `defineVaporComponent` : `defineComponent`,
       )}({${def}${runtimeOptions}\n  ${
         hasAwait ? `async ` : ``
       }setup(${args}) {\n${exposeCall}`,
diff --git a/packages/compiler-vapor/__tests__/transforms/__snapshots__/vBind.spec.ts.snap b/packages/compiler-vapor/__tests__/transforms/__snapshots__/vBind.spec.ts.snap
index 4e34c1818..4ea0db55f 100644
--- a/packages/compiler-vapor/__tests__/transforms/__snapshots__/vBind.spec.ts.snap
+++ b/packages/compiler-vapor/__tests__/transforms/__snapshots__/vBind.spec.ts.snap
@@ -113,6 +113,35 @@ export function render(_ctx) {
 }"
 `;
 
+exports[`cache multiple access > object property name substring cases 1`] = `
+"import { setProp as _setProp, renderEffect as _renderEffect, template as _template } from 'vue';
+const t0 = _template("<div></div>", true)
+
+export function render(_ctx) {
+  const n0 = t0()
+  _renderEffect(() => {
+    const _p = _ctx.p
+    const _p_title = _p.title
+    _setProp(n0, "id", _p_title + _p.titles + _p_title)
+  })
+  return n0
+}"
+`;
+
+exports[`cache multiple access > optional chaining 1`] = `
+"import { setProp as _setProp, renderEffect as _renderEffect, template as _template } from 'vue';
+const t0 = _template("<div></div>", true)
+
+export function render(_ctx) {
+  const n0 = t0()
+  _renderEffect(() => {
+    const _obj = _ctx.obj
+    _setProp(n0, "id", _obj?.foo + _obj?.bar)
+  })
+  return n0
+}"
+`;
+
 exports[`cache multiple access > repeated expression in expressions 1`] = `
 "import { setProp as _setProp, renderEffect as _renderEffect, template as _template } from 'vue';
 const t0 = _template("<div></div>")
@@ -180,6 +209,20 @@ export function render(_ctx) {
 }"
 `;
 
+exports[`cache multiple access > variable name substring edge cases 1`] = `
+"import { setProp as _setProp, renderEffect as _renderEffect, template as _template } from 'vue';
+const t0 = _template("<div></div>", true)
+
+export function render(_ctx) {
+  const n0 = t0()
+  _renderEffect(() => {
+    const _title = _ctx.title
+    _setProp(n0, "id", _title + _ctx.titles + _title)
+  })
+  return n0
+}"
+`;
+
 exports[`compiler v-bind > .attr modifier 1`] = `
 "import { setAttr as _setAttr, renderEffect as _renderEffect, template as _template } from 'vue';
 const t0 = _template("<div></div>", true)
diff --git a/packages/compiler-vapor/__tests__/transforms/vBind.spec.ts b/packages/compiler-vapor/__tests__/transforms/vBind.spec.ts
index 60c3ebf0c..e96186c27 100644
--- a/packages/compiler-vapor/__tests__/transforms/vBind.spec.ts
+++ b/packages/compiler-vapor/__tests__/transforms/vBind.spec.ts
@@ -785,6 +785,25 @@ describe('cache multiple access', () => {
     expect(code).contains('_setProp(n0, "id", _obj[1][_ctx.baz] + _obj.bar)')
   })
 
+  test('variable name substring edge cases', () => {
+    const { code } = compileWithVBind(
+      `<div :id="title + titles + title"></div>`,
+    )
+    expect(code).matchSnapshot()
+    expect(code).contains('const _title = _ctx.title')
+    expect(code).contains('_setProp(n0, "id", _title + _ctx.titles + _title)')
+  })
+
+  test('object property name substring cases', () => {
+    const { code } = compileWithVBind(
+      `<div :id="p.title + p.titles + p.title"></div>`,
+    )
+    expect(code).matchSnapshot()
+    expect(code).contains('const _p = _ctx.p')
+    expect(code).contains('const _p_title = _p.title')
+    expect(code).contains('_setProp(n0, "id", _p_title + _p.titles + _p_title)')
+  })
+
   test('cache variable used in both property shorthand and normal binding', () => {
     const { code } = compileWithVBind(`
         <div :style="{color}" :id="color"/>
@@ -794,6 +813,13 @@ describe('cache multiple access', () => {
     expect(code).contains('_setStyle(n0, {color: _color})')
   })
 
+  test('optional chaining', () => {
+    const { code } = compileWithVBind(`<div :id="obj?.foo + obj?.bar"></div>`)
+    expect(code).matchSnapshot()
+    expect(code).contains('const _obj = _ctx.obj')
+    expect(code).contains('_setProp(n0, "id", _obj?.foo + _obj?.bar)')
+  })
+
   test('not cache variable only used in property shorthand', () => {
     const { code } = compileWithVBind(`
         <div :style="{color}" />
diff --git a/packages/compiler-vapor/src/generators/expression.ts b/packages/compiler-vapor/src/generators/expression.ts
index 845c8bedd..a8fbc8f83 100644
--- a/packages/compiler-vapor/src/generators/expression.ts
+++ b/packages/compiler-vapor/src/generators/expression.ts
@@ -283,7 +283,13 @@ export function processExpressions(
 function analyzeExpressions(expressions: SimpleExpressionNode[]) {
   const seenVariable: Record<string, number> = Object.create(null)
   const variableToExpMap = new Map<string, Set<SimpleExpressionNode>>()
-  const expToVariableMap = new Map<SimpleExpressionNode, string[]>()
+  const expToVariableMap = new Map<
+    SimpleExpressionNode,
+    Array<{
+      name: string
+      loc?: { start: number; end: number }
+    }>
+  >()
   const seenIdentifier = new Set<string>()
   const updatedVariable = new Set<string>()
 
@@ -291,6 +297,7 @@ function analyzeExpressions(expressions: SimpleExpressionNode[]) {
     name: string,
     exp: SimpleExpressionNode,
     isIdentifier: boolean,
+    loc?: { start: number; end: number },
     parentStack: Node[] = [],
   ) => {
     if (isIdentifier) seenIdentifier.add(name)
@@ -299,7 +306,11 @@ function analyzeExpressions(expressions: SimpleExpressionNode[]) {
       name,
       (variableToExpMap.get(name) || new Set()).add(exp),
     )
-    expToVariableMap.set(exp, (expToVariableMap.get(exp) || []).concat(name))
+
+    const variables = expToVariableMap.get(exp) || []
+    variables.push({ name, loc })
+    expToVariableMap.set(exp, variables)
+
     if (
       parentStack.some(
         p => p.type === 'UpdateExpression' || p.type === 'AssignmentExpression',
@@ -317,12 +328,27 @@ function analyzeExpressions(expressions: SimpleExpressionNode[]) {
 
     walkIdentifiers(exp.ast, (currentNode, parent, parentStack) => {
       if (parent && isMemberExpression(parent)) {
-        const memberExp = extractMemberExpression(parent, name => {
-          registerVariable(name, exp, true)
+        const memberExp = extractMemberExpression(parent, id => {
+          registerVariable(id.name, exp, true, {
+            start: id.start!,
+            end: id.end!,
+          })
         })
-        registerVariable(memberExp, exp, false, parentStack)
+        registerVariable(
+          memberExp,
+          exp,
+          false,
+          { start: parent.start!, end: parent.end! },
+          parentStack,
+        )
       } else if (!parentStack.some(isMemberExpression)) {
-        registerVariable(currentNode.name, exp, true, parentStack)
+        registerVariable(
+          currentNode.name,
+          exp,
+          true,
+          { start: currentNode.start!, end: currentNode.end! },
+          parentStack,
+        )
       }
     })
   }
@@ -340,11 +366,22 @@ function processRepeatedVariables(
   context: CodegenContext,
   seenVariable: Record<string, number>,
   variableToExpMap: Map<string, Set<SimpleExpressionNode>>,
-  expToVariableMap: Map<SimpleExpressionNode, string[]>,
+  expToVariableMap: Map<
+    SimpleExpressionNode,
+    Array<{ name: string; loc?: { start: number; end: number } }>
+  >,
   seenIdentifier: Set<string>,
   updatedVariable: Set<string>,
 ): DeclarationValue[] {
   const declarations: DeclarationValue[] = []
+  const expToReplacementMap = new Map<
+    SimpleExpressionNode,
+    Array<{
+      name: string
+      locs: { start: number; end: number }[]
+    }>
+  >()
+
   for (const [name, exps] of variableToExpMap) {
     if (updatedVariable.has(name)) continue
     if (seenVariable[name] > 1 && exps.size > 0) {
@@ -356,12 +393,20 @@ function processRepeatedVariables(
       // e.g., foo[baz] -> foo_baz.
       // for identifiers, we don't need to replace the content - they will be
       // replaced during context.withId(..., ids)
-      const replaceRE = new RegExp(escapeRegExp(name), 'g')
       exps.forEach(node => {
-        if (node.ast) {
-          node.content = node.content.replace(replaceRE, varName)
-          // re-parse the expression
-          node.ast = parseExp(context, node.content)
+        if (node.ast && varName !== name) {
+          const replacements = expToReplacementMap.get(node) || []
+          replacements.push({
+            name: varName,
+            locs: expToVariableMap.get(node)!.reduce(
+              (locs, v) => {
+                if (v.name === name && v.loc) locs.push(v.loc)
+                return locs
+              },
+              [] as { start: number; end: number }[],
+            ),
+          })
+          expToReplacementMap.set(node, replacements)
         }
       })
 
@@ -384,15 +429,35 @@ function processRepeatedVariables(
     }
   }
 
+  for (const [exp, replacements] of expToReplacementMap) {
+    replacements
+      .flatMap(({ name, locs }) =>
+        locs.map(({ start, end }) => ({ start, end, name })),
+      )
+      .sort((a, b) => b.end - a.end)
+      .forEach(({ start, end, name }) => {
+        exp.content =
+          exp.content.slice(0, start - 1) + name + exp.content.slice(end - 1)
+      })
+
+    // re-parse the expression
+    exp.ast = parseExp(context, exp.content)
+  }
+
   return declarations
 }
 
 function shouldDeclareVariable(
   name: string,
-  expToVariableMap: Map<SimpleExpressionNode, string[]>,
+  expToVariableMap: Map<
+    SimpleExpressionNode,
+    Array<{ name: string; loc?: { start: number; end: number } }>
+  >,
   exps: Set<SimpleExpressionNode>,
 ): boolean {
-  const vars = Array.from(exps, exp => expToVariableMap.get(exp)!)
+  const vars = Array.from(exps, exp =>
+    expToVariableMap.get(exp)!.map(v => v.name),
+  )
   // assume name equals to `foo`
   // if each expression only references `foo`, declaration is needed
   // to avoid reactivity tracking
@@ -439,12 +504,15 @@ function processRepeatedExpressions(
   expressions: SimpleExpressionNode[],
   varDeclarations: DeclarationValue[],
   updatedVariable: Set<string>,
-  expToVariableMap: Map<SimpleExpressionNode, string[]>,
+  expToVariableMap: Map<
+    SimpleExpressionNode,
+    Array<{ name: string; loc?: { start: number; end: number } }>
+  >,
 ): DeclarationValue[] {
   const declarations: DeclarationValue[] = []
   const seenExp = expressions.reduce(
     (acc, exp) => {
-      const variables = expToVariableMap.get(exp)
+      const variables = expToVariableMap.get(exp)!.map(v => v.name)
       // only handle expressions that are not identifiers
       if (
         exp.ast &&
@@ -572,12 +640,12 @@ function genVarName(exp: string): string {
 
 function extractMemberExpression(
   exp: Node,
-  onIdentifier: (name: string) => void,
+  onIdentifier: (id: Identifier) => void,
 ): string {
   if (!exp) return ''
   switch (exp.type) {
     case 'Identifier': // foo[bar]
-      onIdentifier(exp.name)
+      onIdentifier(exp)
       return exp.name
     case 'StringLiteral': // foo['bar']
       return exp.extra ? (exp.extra.raw as string) : exp.value
@@ -588,6 +656,7 @@ function extractMemberExpression(
     case 'CallExpression': // foo[bar(baz)]
       return `${extractMemberExpression(exp.callee, onIdentifier)}(${exp.arguments.map(arg => extractMemberExpression(arg, onIdentifier)).join(', ')})`
     case 'MemberExpression': // foo[bar.baz]
+    case 'OptionalMemberExpression': // foo?.bar
       const object = extractMemberExpression(exp.object, onIdentifier)
       const prop = exp.computed
         ? `[${extractMemberExpression(exp.property, onIdentifier)}]`
diff --git a/packages/runtime-vapor/src/vdomInterop.ts b/packages/runtime-vapor/src/vdomInterop.ts
index 3365910ce..9d90f7230 100644
--- a/packages/runtime-vapor/src/vdomInterop.ts
+++ b/packages/runtime-vapor/src/vdomInterop.ts
@@ -18,6 +18,7 @@ import {
   isEmitListener,
   onScopeDispose,
   renderSlot,
+  shallowReactive,
   shallowRef,
   simpleSetCurrentInstance,
 } from '@vue/runtime-dom'
@@ -187,7 +188,8 @@ function createVDOMComponent(
 
   // overwrite how the vdom instance handles props
   vnode.vi = (instance: ComponentInternalInstance) => {
-    instance.props = wrapper.props
+    // ensure props are shallow reactive to align with VDOM behavior.
+    instance.props = shallowReactive(wrapper.props)
 
     const attrs = (instance.attrs = createInternalObject())
     for (const key in wrapper.attrs) {