diff --git a/src/use-swr.ts b/src/use-swr.ts
index f54e78e30..4ddcc8191 100644
--- a/src/use-swr.ts
+++ b/src/use-swr.ts
@@ -49,13 +49,8 @@ export const useSWRHandler = <Data = any, Error = any>(
     refreshWhenOffline
   } = config
 
-  const [
-    EVENT_REVALIDATORS,
-    STATE_UPDATERS,
-    MUTATION_TS,
-    MUTATION_END_TS,
-    CONCURRENT_REQUESTS
-  ] = SWRGlobalState.get(cache) as GlobalState
+  const [EVENT_REVALIDATORS, STATE_UPDATERS, MUTATION, CONCURRENT_REQUESTS] =
+    SWRGlobalState.get(cache) as GlobalState
 
   // `key` is the identifier of the SWR `data` state, `keyErr` and
   // `keyValidating` are identifiers of `error` and `isValidating`,
@@ -249,14 +244,15 @@ export const useSWRHandler = <Data = any, Error = any>(
         //       mutate-------...---------->
         // we have to ignore the revalidation result (res) because it's no longer fresh.
         // meanwhile, a new revalidation should be triggered when the mutation ends.
+        const mutationInfo = MUTATION[key]
         if (
-          !isUndefined(MUTATION_TS[key]) &&
+          !isUndefined(mutationInfo) &&
           // case 1
-          (startAt <= MUTATION_TS[key] ||
+          (startAt <= mutationInfo[0] ||
             // case 2
-            startAt <= MUTATION_END_TS[key] ||
+            startAt <= mutationInfo[1] ||
             // case 3
-            MUTATION_END_TS[key] === 0)
+            mutationInfo[1] === 0)
         ) {
           finishRequestAndUpdateState()
           if (shouldStartNewRequest) {
diff --git a/src/utils/broadcast-state.ts b/src/utils/broadcast-state.ts
index 939cca939..9725995ef 100644
--- a/src/utils/broadcast-state.ts
+++ b/src/utils/broadcast-state.ts
@@ -11,7 +11,7 @@ export const broadcastState: Broadcaster = (
   revalidate,
   broadcast = true
 ) => {
-  const [EVENT_REVALIDATORS, STATE_UPDATERS, , , CONCURRENT_REQUESTS] =
+  const [EVENT_REVALIDATORS, STATE_UPDATERS, , CONCURRENT_REQUESTS] =
     SWRGlobalState.get(cache) as GlobalState
   const revalidators = EVENT_REVALIDATORS[key]
   const updaters = STATE_UPDATERS[key]
diff --git a/src/utils/cache.ts b/src/utils/cache.ts
index 04d10fbc2..7ff30f4a8 100644
--- a/src/utils/cache.ts
+++ b/src/utils/cache.ts
@@ -48,7 +48,7 @@ export const initCache = <Data = any>(
     let unmount = noop
 
     // Update the state if it's new, or the provider has been extended.
-    SWRGlobalState.set(provider, [EVENT_REVALIDATORS, {}, {}, {}, {}, mutate])
+    SWRGlobalState.set(provider, [EVENT_REVALIDATORS, {}, {}, {}, mutate])
 
     // This is a new provider, we need to initialize it and setup DOM events
     // listeners for `focus` and `reconnect` actions.
@@ -96,5 +96,5 @@ export const initCache = <Data = any>(
     return [provider, mutate, unmount]
   }
 
-  return [provider, (SWRGlobalState.get(provider) as GlobalState)[5]]
+  return [provider, (SWRGlobalState.get(provider) as GlobalState)[4]]
 }
diff --git a/src/utils/global-state.ts b/src/utils/global-state.ts
index a57d4d42d..2116cce99 100644
--- a/src/utils/global-state.ts
+++ b/src/utils/global-state.ts
@@ -8,8 +8,7 @@ import {
 export type GlobalState = [
   Record<string, RevalidateCallback[]>, // EVENT_REVALIDATORS
   Record<string, StateUpdateCallback[]>, // STATE_UPDATERS
-  Record<string, number>, // MUTATION_TS
-  Record<string, number>, // MUTATION_END_TS
+  Record<string, [number, number]>, // MUTATION: [ts, end_ts]
   Record<string, [any, number]>, // CONCURRENT_REQUESTS: [data, ts]
   ScopedMutator // Mutator
 ]
diff --git a/src/utils/mutate.ts b/src/utils/mutate.ts
index 1812e0c51..f77c0293f 100644
--- a/src/utils/mutate.ts
+++ b/src/utils/mutate.ts
@@ -31,9 +31,7 @@ export const internalMutate = async <Data>(
   const [key, , keyErr] = serialize(_key)
   if (!key) return
 
-  const [, , MUTATION_TS, MUTATION_END_TS] = SWRGlobalState.get(
-    cache
-  ) as GlobalState
+  const [, , MUTATION] = SWRGlobalState.get(cache) as GlobalState
 
   // If there is no new data provided, revalidate the key with current state.
   if (args.length < 3) {
@@ -53,8 +51,8 @@ export const internalMutate = async <Data>(
   let error: unknown
 
   // Update global timestamps.
-  const beforeMutationTs = (MUTATION_TS[key] = getTimestamp())
-  MUTATION_END_TS[key] = 0
+  const beforeMutationTs = getTimestamp()
+  MUTATION[key] = [beforeMutationTs, 0]
   const hasOptimisticData = !isUndefined(optimisticData)
   const rollbackData = cache.get(key)
 
@@ -85,7 +83,7 @@ export const internalMutate = async <Data>(
     // Check if other mutations have occurred since we've started this mutation.
     // If there's a race we don't update cache or broadcast the change,
     // just return the data.
-    if (beforeMutationTs !== MUTATION_TS[key]) {
+    if (beforeMutationTs !== MUTATION[key][0]) {
       if (error) throw error
       return data
     } else if (error && hasOptimisticData && rollbackOnError) {
@@ -106,7 +104,7 @@ export const internalMutate = async <Data>(
   }
 
   // Reset the timestamp to mark the mutation has ended.
-  MUTATION_END_TS[key] = getTimestamp()
+  MUTATION[key][1] = getTimestamp()
 
   // Update existing SWR Hooks' internal states:
   const res = await broadcastState(