diff --git a/modules/repository/repo.go b/modules/repository/repo.go
index 5af69763d..5352da037 100644
--- a/modules/repository/repo.go
+++ b/modules/repository/repo.go
@@ -508,6 +508,18 @@ func StoreMissingLfsObjectsInRepository(ctx context.Context, repo *repo_model.Re
 	return nil
 }
 
+// shortRelease to reduce load memory, this struct can replace repo_model.Release
+type shortRelease struct {
+	ID      int64
+	TagName string
+	Sha1    string
+	IsTag   bool
+}
+
+func (shortRelease) TableName() string {
+	return "release"
+}
+
 // pullMirrorReleaseSync is a pull-mirror specific tag<->release table
 // synchronization which overwrites all Releases from the repository tags. This
 // can be relied on since a pull-mirror is always identical to its
@@ -521,16 +533,20 @@ func pullMirrorReleaseSync(ctx context.Context, repo *repo_model.Repository, git
 		return fmt.Errorf("unable to GetTagInfos in pull-mirror Repo[%d:%s/%s]: %w", repo.ID, repo.OwnerName, repo.Name, err)
 	}
 	err = db.WithTx(ctx, func(ctx context.Context) error {
-		//
-		// clear out existing releases
-		//
-		if _, err := db.DeleteByBean(ctx, &repo_model.Release{RepoID: repo.ID}); err != nil {
-			return fmt.Errorf("unable to clear releases for pull-mirror Repo[%d:%s/%s]: %w", repo.ID, repo.OwnerName, repo.Name, err)
+		dbReleases, err := db.Find[shortRelease](ctx, repo_model.FindReleasesOptions{
+			RepoID:        repo.ID,
+			IncludeDrafts: true,
+			IncludeTags:   true,
+		})
+		if err != nil {
+			return fmt.Errorf("unable to FindReleases in pull-mirror Repo[%d:%s/%s]: %w", repo.ID, repo.OwnerName, repo.Name, err)
 		}
+
+		inserts, deletes, updates := calcSync(tags, dbReleases)
 		//
 		// make release set identical to upstream tags
 		//
-		for _, tag := range tags {
+		for _, tag := range inserts {
 			release := repo_model.Release{
 				RepoID:       repo.ID,
 				TagName:      tag.Name,
@@ -547,6 +563,25 @@ func pullMirrorReleaseSync(ctx context.Context, repo *repo_model.Repository, git
 				return fmt.Errorf("unable insert tag %s for pull-mirror Repo[%d:%s/%s]: %w", tag.Name, repo.ID, repo.OwnerName, repo.Name, err)
 			}
 		}
+
+		// only delete tags releases
+		if len(deletes) > 0 {
+			if _, err := db.GetEngine(ctx).Where("repo_id=?", repo.ID).
+				In("id", deletes).
+				Delete(&repo_model.Release{}); err != nil {
+				return fmt.Errorf("unable to delete tags for pull-mirror Repo[%d:%s/%s]: %w", repo.ID, repo.OwnerName, repo.Name, err)
+			}
+		}
+
+		for _, tag := range updates {
+			if _, err := db.GetEngine(ctx).Where("repo_id = ? AND lower_tag_name = ?", repo.ID, strings.ToLower(tag.Name)).
+				Cols("sha1").
+				Update(&repo_model.Release{
+					Sha1: tag.Object.String(),
+				}); err != nil {
+				return fmt.Errorf("unable to update tag %s for pull-mirror Repo[%d:%s/%s]: %w", tag.Name, repo.ID, repo.OwnerName, repo.Name, err)
+			}
+		}
 		return nil
 	})
 	if err != nil {
@@ -556,3 +591,32 @@ func pullMirrorReleaseSync(ctx context.Context, repo *repo_model.Repository, git
 	log.Trace("pullMirrorReleaseSync: done rebuilding %d releases", numTags)
 	return nil
 }
+
+func calcSync(destTags []*git.Tag, dbTags []*shortRelease) ([]*git.Tag, []int64, []*git.Tag) {
+	destTagMap := make(map[string]*git.Tag)
+	for _, tag := range destTags {
+		destTagMap[tag.Name] = tag
+	}
+	dbTagMap := make(map[string]*shortRelease)
+	for _, rel := range dbTags {
+		dbTagMap[rel.TagName] = rel
+	}
+
+	inserted := make([]*git.Tag, 0, 10)
+	updated := make([]*git.Tag, 0, 10)
+	for _, tag := range destTags {
+		rel := dbTagMap[tag.Name]
+		if rel == nil {
+			inserted = append(inserted, tag)
+		} else if rel.Sha1 != tag.Object.String() {
+			updated = append(updated, tag)
+		}
+	}
+	deleted := make([]int64, 0, 10)
+	for _, tag := range dbTags {
+		if destTagMap[tag.TagName] == nil && tag.IsTag {
+			deleted = append(deleted, tag.ID)
+		}
+	}
+	return inserted, deleted, updated
+}
diff --git a/modules/repository/repo_test.go b/modules/repository/repo_test.go
new file mode 100644
index 000000000..68980f92f
--- /dev/null
+++ b/modules/repository/repo_test.go
@@ -0,0 +1,76 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repository
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/modules/git"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_calcSync(t *testing.T) {
+	gitTags := []*git.Tag{
+		/*{
+			Name: "v0.1.0-beta", //deleted tag
+			Object: git.MustIDFromString(""),
+		},
+		{
+			Name: "v0.1.1-beta", //deleted tag but release should not be deleted because it's a release
+			Object: git.MustIDFromString(""),
+		},
+		*/
+		{
+			Name:   "v1.0.0", // keep as before
+			Object: git.MustIDFromString("1006e6e13c73ad3d9e2d5682ad266b5016523485"),
+		},
+		{
+			Name:   "v1.1.0", // retagged with new commit id
+			Object: git.MustIDFromString("bbdb7df30248e7d4a26a909c8d2598a152e13868"),
+		},
+		{
+			Name:   "v1.2.0", // new tag
+			Object: git.MustIDFromString("a5147145e2f24d89fd6d2a87826384cc1d253267"),
+		},
+	}
+
+	dbReleases := []*shortRelease{
+		{
+			ID:      1,
+			TagName: "v0.1.0-beta",
+			Sha1:    "244758d7da8dd1d9e0727e8cb7704ed4ba9a17c3",
+			IsTag:   true,
+		},
+		{
+			ID:      2,
+			TagName: "v0.1.1-beta",
+			Sha1:    "244758d7da8dd1d9e0727e8cb7704ed4ba9a17c3",
+			IsTag:   false,
+		},
+		{
+			ID:      3,
+			TagName: "v1.0.0",
+			Sha1:    "1006e6e13c73ad3d9e2d5682ad266b5016523485",
+		},
+		{
+			ID:      4,
+			TagName: "v1.1.0",
+			Sha1:    "53ab18dcecf4152b58328d1f47429510eb414d50",
+		},
+	}
+
+	inserts, deletes, updates := calcSync(gitTags, dbReleases)
+	if assert.EqualValues(t, 1, len(inserts), "inserts") {
+		assert.EqualValues(t, *gitTags[2], *inserts[0], "inserts equal")
+	}
+
+	if assert.EqualValues(t, 1, len(deletes), "deletes") {
+		assert.EqualValues(t, 1, deletes[0], "deletes equal")
+	}
+
+	if assert.EqualValues(t, 1, len(updates), "updates") {
+		assert.EqualValues(t, *gitTags[1], *updates[0], "updates equal")
+	}
+}