diff --git a/core/services/ocr2/plugins/promwrapper/plugin.go b/core/services/ocr2/plugins/promwrapper/plugin.go
index cc6c9d135dd..448c2ed2ddf 100644
--- a/core/services/ocr2/plugins/promwrapper/plugin.go
+++ b/core/services/ocr2/plugins/promwrapper/plugin.go
@@ -5,17 +5,27 @@ package promwrapper
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"math/big"
 	"sync"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/patrickmn/go-cache"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/smartcontractkit/libocr/offchainreporting2plus/types"
 )
 
+const (
+	// DefaultExpiration is the default expiration time for cache items.
+	DefaultExpiration = 2 * time.Hour
+
+	// DefaultCleanupInterval is the default interval for cache cleanup.
+	DefaultCleanupInterval = 30 * time.Minute
+)
+
 // Type assertions, buckets and labels.
 var (
 	_       types.ReportingPlugin = &promPlugin{}
@@ -162,7 +172,7 @@ type (
 		configDigest                  string
 		queryEndTimes                 sync.Map
 		observationEndTimes           sync.Map
-		reportEndTimes                sync.Map
+		reportEndTimes                *cache.Cache
 		acceptFinalizedReportEndTimes sync.Map
 		prometheusBackend             PrometheusBackend
 	}
@@ -230,6 +240,7 @@ func New(
 		oracleID:          fmt.Sprintf("%d", config.OracleID),
 		configDigest:      common.Bytes2Hex(config.ConfigDigest[:]),
 		prometheusBackend: prometheusBackend,
+		reportEndTimes:    cache.New(DefaultExpiration, DefaultCleanupInterval),
 	}
 }
 
@@ -280,21 +291,33 @@ func (p *promPlugin) Report(ctx context.Context, timestamp types.ReportTimestamp
 	defer func() {
 		duration := float64(time.Now().UTC().Sub(start))
 		p.prometheusBackend.SetReportDuration(labelValues, duration)
-		p.reportEndTimes.Store(timestamp, time.Now().UTC()) // note time at end of Report()
+
+		// hash the timestamp
+		key := timestampToKey(timestamp)
+		p.reportEndTimes.Set(key, time.Now().UTC(), cache.DefaultExpiration) // note time at end of Report()
 	}()
 
 	return p.wrapped.Report(ctx, timestamp, query, observations)
 }
 
+func timestampToKey(timestamp types.ReportTimestamp) string {
+	jsonData, _ := json.Marshal(timestamp)
+	key := string(jsonData)
+	return key
+}
+
 func (p *promPlugin) ShouldAcceptFinalizedReport(ctx context.Context, timestamp types.ReportTimestamp, report types.Report) (bool, error) {
 	start := time.Now().UTC()
 
+	jsonData, _ := json.Marshal(timestamp)
+	key := string(jsonData)
+
 	// Report latency between Report() and ShouldAcceptFinalizedReport().
 	labelValues := getLabelsValues(p, timestamp)
-	if reportEndTime, ok := p.reportEndTimes.Load(timestamp); ok {
+	if reportEndTime, ok := p.reportEndTimes.Get(key); ok {
 		latency := float64(start.Sub(reportEndTime.(time.Time)))
 		p.prometheusBackend.SetReportToAcceptFinalizedReportLatency(labelValues, latency)
-		p.reportEndTimes.Delete(timestamp)
+		p.reportEndTimes.Delete(key)
 	}
 
 	// Report latency for ShouldAcceptFinalizedReport() at end of call.
diff --git a/core/services/ocr2/plugins/promwrapper/plugin_test.go b/core/services/ocr2/plugins/promwrapper/plugin_test.go
index b4de7f027f3..12ecf080ba1 100644
--- a/core/services/ocr2/plugins/promwrapper/plugin_test.go
+++ b/core/services/ocr2/plugins/promwrapper/plugin_test.go
@@ -217,13 +217,13 @@ func TestPlugin_GetLatencies(t *testing.T) {
 	require.NoError(t, err)
 	_, ok = promPlugin.observationEndTimes.Load(reportTimestamp)
 	require.Equal(t, false, ok)
-	_, ok = promPlugin.reportEndTimes.Load(reportTimestamp)
+	_, ok = promPlugin.reportEndTimes.Get(timestampToKey(reportTimestamp))
 	require.Equal(t, true, ok)
 	time.Sleep(rToALatency)
 
 	_, err = promPlugin.ShouldAcceptFinalizedReport(ctx, reportTimestamp, nil)
 	require.NoError(t, err)
-	_, ok = promPlugin.reportEndTimes.Load(reportTimestamp)
+	_, ok = promPlugin.reportEndTimes.Get(timestampToKey(reportTimestamp))
 	require.Equal(t, false, ok)
 	_, ok = promPlugin.acceptFinalizedReportEndTimes.Load(reportTimestamp)
 	require.Equal(t, true, ok)