diff --git a/packages/vite/src/node/__tests__/optimizer/discoverBeforeListen.spec.ts b/packages/vite/src/node/__tests__/optimizer/discoverBeforeListen.spec.ts
index 22fa56ee1ba8b2..df883c9fb6ed09 100644
--- a/packages/vite/src/node/__tests__/optimizer/discoverBeforeListen.spec.ts
+++ b/packages/vite/src/node/__tests__/optimizer/discoverBeforeListen.spec.ts
@@ -90,3 +90,35 @@ test('does not crash when a dep is discovered before the server starts listening
   await ssr.depsOptimizer?.scanProcessing
   expect(errors).toStrictEqual([])
 })
+
+// regression test for https://github.com/vitejs/vite/issues/23143
+// When a module importing a bare specifier is transformed without calling `server.listen()`,
+// calling `server.close()` should not hang waiting for optimizer processing promises.
+test('server.close() resolves promptly when deps were discovered without calling listen()', async () => {
+  server = await createServer({
+    configFile: false,
+    root: path.join(
+      import.meta.dirname,
+      '../fixtures/optimizer-discover-before-listen',
+    ),
+    environments: {
+      client: {
+        optimizeDeps: {
+          force: true,
+        },
+      },
+    },
+  })
+
+  await server.environments.client.transformRequest('/entry.js')
+
+  const closePromise = server.close()
+  const timeoutPromise = setTimeout(2000).then(() => {
+    throw new Error('server.close() timed out')
+  })
+
+  await expect(
+    Promise.race([closePromise, timeoutPromise]),
+  ).resolves.toBeUndefined()
+  server = undefined
+})
diff --git a/packages/vite/src/node/optimizer/index.ts b/packages/vite/src/node/optimizer/index.ts
index 9289c5327feb69..26719ded616a86 100644
--- a/packages/vite/src/node/optimizer/index.ts
+++ b/packages/vite/src/node/optimizer/index.ts
@@ -68,6 +68,7 @@ export interface DepsOptimizer {
   getOptimizedDepId: (depInfo: OptimizedDepInfo) => string
 
   close: () => Promise<void>
+  isClosed?: () => boolean
 
   options: DepOptimizationOptions
 }
diff --git a/packages/vite/src/node/optimizer/optimizer.ts b/packages/vite/src/node/optimizer/optimizer.ts
index b6a63c038d3614..02d8a5687c88a4 100644
--- a/packages/vite/src/node/optimizer/optimizer.ts
+++ b/packages/vite/src/node/optimizer/optimizer.ts
@@ -66,6 +66,7 @@ export function createDepsOptimizer(
     getOptimizedDepId: (depInfo: OptimizedDepInfo) =>
       `${depInfo.file}?v=${depInfo.browserHash}`,
     close,
+    isClosed: () => closed,
     options,
   }
 
@@ -147,6 +148,16 @@ export function createDepsOptimizer(
 
   async function close() {
     closed = true
+    if (debounceProcessingHandle) {
+      clearTimeout(debounceProcessingHandle)
+      debounceProcessingHandle = undefined
+    }
+    if (newDepsToLogHandle) {
+      clearTimeout(newDepsToLogHandle)
+      newDepsToLogHandle = undefined
+    }
+    resolveEnqueuedProcessingPromises()
+    depOptimizationProcessing.resolve()
     await Promise.allSettled([
       discover?.cancel(),
       depsOptimizer.scanProcessing,
@@ -753,6 +764,7 @@ export function createDepsOptimizer(
 export function createExplicitDepsOptimizer(
   environment: DevEnvironment,
 ): DepsOptimizer {
+  let closed = false
   const depsOptimizer = {
     metadata: initDepsOptimizerMetadata(environment),
     isOptimizedDepFile: createIsOptimizedDepFile(environment),
@@ -770,7 +782,10 @@ export function createExplicitDepsOptimizer(
     // the optimizer blocks the server start
     run: () => {},
 
-    close: async () => {},
+    close: async () => {
+      closed = true
+    },
+    isClosed: () => closed,
     options: environment.config.optimizeDeps,
   }
 
diff --git a/packages/vite/src/node/plugins/optimizedDeps.ts b/packages/vite/src/node/plugins/optimizedDeps.ts
index cde478bf2c6839..2e68267b31da8a 100644
--- a/packages/vite/src/node/plugins/optimizedDeps.ts
+++ b/packages/vite/src/node/plugins/optimizedDeps.ts
@@ -100,6 +100,9 @@ export function optimizedDepsPlugin(): Plugin {
           }
           return code
         } catch {
+          if (depsOptimizer?.isClosed?.()) {
+            return null
+          }
           if (
             browserHash &&
             !environment.config.optimizeDeps.ignoreOutdatedRequests