diff --git a/config.yaml b/config.yaml
index d8f4d00..dc909fc 100644
--- a/config.yaml
+++ b/config.yaml
@@ -70,6 +70,21 @@ ui:
   # Number of commits to display in a single "Commits" (log) page.
   commitsPageSize: 30
 
+  diff:
+    # When a total line count of added and deleted lines exceeds this value,
+    # default UI hides diff view for the file and displays an interactive
+    # element to reveal the diff lazily.
+    #
+    # Displaying large diffs slows browser's rendering process down significantly.
+    # This option prevents surprising slow loading: user may not know the commit
+    # contains large diffs prior to visit.
+    #
+    # The does not affect server load for large diffs. For server-side diff
+    # generation performance, see "repo.diff" config option.
+    #
+    # Setting 0 disables the hiding mechanism. Default value is 0.
+    hideThresholdLines: 1000
+
   # You can set repository's category by creating `category` file in $GIT_DIR or
   # setting `gitweb.category` git config.
   # https://git-scm.com/docs/gitweb#Documentation/gitweb.txt-categoryorgitwebcategory
diff --git a/config/config.go b/config/config.go
index 6f7f848..2eb83a4 100644
--- a/config/config.go
+++ b/config/config.go
@@ -35,7 +35,12 @@ type Config struct {
 	} `yaml:"meta"`
 	UI struct {
 		CommitsPageSize uint32 `yaml:"commitsPageSize"`
-		Category        struct {
+		Diff            struct {
+			// HideThresholdLines controls threshold to hide diff for the file.
+			// Unit is line count, and set 0 to disable diff hiding at all.
+			HideThresholdLines uint32 `yaml:"hideThresholdLines"`
+		}
+		Category struct {
 			Grouping bool     `yaml:"grouping"`
 			Default  string   `yaml:"default"`
 			Order    []string `yaml:"order"`
diff --git a/demo/config.yaml b/demo/config.yaml
index f8ea6e6..39641f7 100644
--- a/demo/config.yaml
+++ b/demo/config.yaml
@@ -47,6 +47,9 @@ ui:
       - "Mirror"
       - "Abandoned"
 
+  diff:
+    hideThresholdLines: 1000
+
   footer:
     links:
       - text: Hosted
diff --git a/embed/templates/repo-commit.html.tmpl b/embed/templates/repo-commit.html.tmpl
index da4871c..7001dde 100644
--- a/embed/templates/repo-commit.html.tmpl
+++ b/embed/templates/repo-commit.html.tmpl
@@ -66,6 +66,10 @@ SPDX-License-Identifier: MIT
 							{{ if .IsBinary -}}
 							<p>Diff for binary file is unavailable.</p>
 							{{- else -}}
+							{{- if $root.IsLargeDiff . -}}
+							<details>
+							<summary>Diff ({{ $root.FileDiffStat . }})</summary>
+							{{- end -}}
 							<ul class="repo-commit--diff">
 								{{- range .TextFragments }}
 								<li class="repo-commit--diff-item">
@@ -93,6 +97,9 @@ SPDX-License-Identifier: MIT
 								</li>
 								{{ end -}}
 							</ul>
+							{{- if $root.IsLargeDiff . -}}
+							</details>
+							{{- end -}}
 							{{- end }}
 						</div>
 					</li>
diff --git a/routes/data.go b/routes/data.go
index 64486f8..9e1f303 100644
--- a/routes/data.go
+++ b/routes/data.go
@@ -6,10 +6,12 @@
 package routes
 
 import (
+	"fmt"
 	"html/template"
 	"maps"
 	"slices"
 
+	"github.com/bluekeyes/go-gitdiff/gitdiff"
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/object"
 	"github.com/pocka/legit/config"
@@ -241,6 +243,33 @@ type repoCommitData struct {
 	Diff *git.NiceDiff
 }
 
+func (r repoCommitData) IsLargeDiff(file *gitdiff.File) bool {
+	if r.Config.UI.Diff.HideThresholdLines == 0 {
+		return false
+	}
+
+	var n uint32
+
+	for _, fragment := range file.TextFragments {
+		n += uint32(max(0, fragment.LinesAdded))
+		n += uint32(max(0, fragment.LinesDeleted))
+	}
+
+	return n > r.Config.UI.Diff.HideThresholdLines
+}
+
+func (r repoCommitData) FileDiffStat(file *gitdiff.File) string {
+	var added int64
+	var deleted int64
+
+	for _, fragment := range file.TextFragments {
+		added += fragment.LinesAdded
+		deleted += fragment.LinesDeleted
+	}
+
+	return fmt.Sprintf("+%d/-%d", added, deleted)
+}
+
 // error404Data is a data object passed to "404" template.
 type error404Data struct {
 	// Config represents a resolved config based on "config.yaml".