diff --git a/dataset/dataset.go b/dataset/dataset.go
index aba119c66..6a571c123 100644
--- a/dataset/dataset.go
+++ b/dataset/dataset.go
@@ -18,6 +18,7 @@ import (
 	"time"
 
 	"github.com/chewxy/math32"
+	mapset "github.com/deckarep/golang-set/v2"
 	"github.com/samber/lo"
 	"github.com/zhenghaoz/gorse/storage/data"
 	"modernc.org/strutil"
@@ -35,6 +36,7 @@ type Dataset struct {
 	itemFeedback [][]ID
 	userDict     *FreqDict
 	itemDict     *FreqDict
+	categories   mapset.Set[string]
 }
 
 func NewDataset(timestamp time.Time, userCount, itemCount int) *Dataset {
@@ -48,6 +50,7 @@ func NewDataset(timestamp time.Time, userCount, itemCount int) *Dataset {
 		itemFeedback: make([][]ID, itemCount),
 		userDict:     NewFreqDict(),
 		itemDict:     NewFreqDict(),
+		categories:   mapset.NewSet[string](),
 	}
 }
 
@@ -71,6 +74,10 @@ func (d *Dataset) GetItemFeedback() [][]ID {
 	return d.itemFeedback
 }
 
+func (d *Dataset) GetCategories() []string {
+	return d.categories.ToSlice()
+}
+
 // GetUserIDF returns the IDF of users.
 //
 //	IDF(u) = log(I/freq(u))
@@ -145,6 +152,7 @@ func (d *Dataset) AddItem(item data.Item) {
 	if len(d.itemFeedback) < len(d.items) {
 		d.itemFeedback = append(d.itemFeedback, nil)
 	}
+	d.categories.Append(item.Categories...)
 }
 
 func (d *Dataset) AddFeedback(userId, itemId string) {
diff --git a/master/tasks.go b/master/tasks.go
index b73ce668f..13947fba7 100644
--- a/master/tasks.go
+++ b/master/tasks.go
@@ -171,7 +171,7 @@ func (m *Master) runLoadDatasetTask() error {
 	InactiveItemsTotal.Set(float64(inactiveItems))
 
 	// write categories to cache
-	if err = m.CacheClient.SetSet(ctx, cache.ItemCategories, rankingDataset.CategorySet.ToSlice()...); err != nil {
+	if err = m.CacheClient.SetSet(ctx, cache.ItemCategories, dataSet.GetCategories()...); err != nil {
 		log.Logger().Error("failed to write categories to cache", zap.Error(err))
 	}
 
@@ -669,10 +669,6 @@ func (m *Master) LoadDataFromDatabase(
 		temp := time.Now().AddDate(0, 0, -int(positiveFeedbackTTL))
 		feedbackTimeLimit = data.WithBeginTime(temp)
 	}
-	timeWindowLimit := time.Time{}
-	if m.Config.Recommend.Popular.PopularWindow > 0 {
-		timeWindowLimit = time.Now().Add(-m.Config.Recommend.Popular.PopularWindow)
-	}
 	rankingDataset = ranking.NewMapIndexDataset()
 
 	// STEP 1: pull users
@@ -742,9 +738,6 @@ func (m *Master) LoadDataFromDatabase(
 			itemIndex := rankingDataset.ItemIndex.ToNumber(item.ItemId)
 			if len(rankingDataset.ItemFeatures) == int(itemIndex) {
 				rankingDataset.ItemFeatures = append(rankingDataset.ItemFeatures, nil)
-				rankingDataset.HiddenItems = append(rankingDataset.HiddenItems, false)
-				rankingDataset.ItemCategories = append(rankingDataset.ItemCategories, item.Categories)
-				rankingDataset.CategorySet.Append(item.Categories...)
 			}
 			features := click.ConvertLabelsToFeatures(item.Labels)
 			rankingDataset.NumItemLabelUsed += len(features)
@@ -772,9 +765,6 @@ func (m *Master) LoadDataFromDatabase(
 					})
 				}
 			}
-			if item.IsHidden { // set hidden flag
-				rankingDataset.HiddenItems[itemIndex] = true
-			}
 			dataSet.AddItem(item)
 		}
 		span.Add(len(batchItems))
@@ -790,7 +780,6 @@ func (m *Master) LoadDataFromDatabase(
 	LoadDatasetStepSecondsVec.WithLabelValues("load_items").Set(time.Since(start).Seconds())
 
 	// create positive set
-	popularCount := make([]int32, rankingDataset.ItemCount())
 	positiveSet := make([]mapset.Set[int32], rankingDataset.UserCount())
 	for i := range positiveSet {
 		positiveSet[i] = mapset.NewSet[int32]()
@@ -835,10 +824,6 @@ func (m *Master) LoadDataFromDatabase(
 				posFeedbackCount++
 				// insert feedback to ranking dataset
 				rankingDataset.AddFeedback(f.UserId, f.ItemId, false)
-				// insert feedback to popularity counter
-				if f.Timestamp.After(timeWindowLimit) && !rankingDataset.HiddenItems[itemIndex] {
-					popularCount[itemIndex]++
-				}
 				// insert feedback to evaluator
 				evaluator.Positive(f.FeedbackType, userIndex, itemIndex, f.Timestamp)
 				mu.Unlock()
diff --git a/model/ranking/data.go b/model/ranking/data.go
index dc9850100..58748487d 100644
--- a/model/ranking/data.go
+++ b/model/ranking/data.go
@@ -31,18 +31,15 @@ import (
 
 // DataSet contains preprocessed data structures for recommendation models.
 type DataSet struct {
-	UserIndex      base.Index
-	ItemIndex      base.Index
-	FeedbackUsers  base.Array[int32]
-	FeedbackItems  base.Array[int32]
-	UserFeedback   [][]int32
-	ItemFeedback   [][]int32
-	Negatives      [][]int32
-	ItemFeatures   [][]lo.Tuple2[int32, float32]
-	UserFeatures   [][]lo.Tuple2[int32, float32]
-	HiddenItems    []bool
-	ItemCategories [][]string
-	CategorySet    mapset.Set[string]
+	UserIndex     base.Index
+	ItemIndex     base.Index
+	FeedbackUsers base.Array[int32]
+	FeedbackItems base.Array[int32]
+	UserFeedback  [][]int32
+	ItemFeedback  [][]int32
+	Negatives     [][]int32
+	ItemFeatures  [][]lo.Tuple2[int32, float32]
+	UserFeatures  [][]lo.Tuple2[int32, float32]
 	// statistics
 	NumItemLabels    int32
 	NumUserLabels    int32
@@ -53,7 +50,6 @@ type DataSet struct {
 // NewMapIndexDataset creates a data set.
 func NewMapIndexDataset() *DataSet {
 	s := new(DataSet)
-	s.CategorySet = mapset.NewSet[string]()
 	// Create index
 	s.UserIndex = base.NewMapIndex()
 	s.ItemIndex = base.NewMapIndex()
@@ -179,9 +175,6 @@ func (dataset *DataSet) Split(numTestUsers int, seed int64) (*DataSet, *DataSet)
 	trainSet, testSet := new(DataSet), new(DataSet)
 	trainSet.NumItemLabels, testSet.NumItemLabels = dataset.NumItemLabels, dataset.NumItemLabels
 	trainSet.NumUserLabels, testSet.NumUserLabels = dataset.NumUserLabels, dataset.NumUserLabels
-	trainSet.HiddenItems, testSet.HiddenItems = dataset.HiddenItems, dataset.HiddenItems
-	trainSet.ItemCategories, testSet.ItemCategories = dataset.ItemCategories, dataset.ItemCategories
-	trainSet.CategorySet, testSet.CategorySet = dataset.CategorySet, dataset.CategorySet
 	trainSet.ItemFeatures, testSet.ItemFeatures = dataset.ItemFeatures, dataset.ItemFeatures
 	trainSet.UserFeatures, testSet.UserFeatures = dataset.UserFeatures, dataset.UserFeatures
 	trainSet.NumItemLabelUsed, testSet.NumItemLabelUsed = dataset.NumItemLabelUsed, dataset.NumItemLabelUsed