diff --git a/DONE.md b/DONE.md
index 189e84b..c05c7c8 100644
--- a/DONE.md
+++ b/DONE.md
@@ -823,6 +823,7 @@ This file tracks completed features, fixes, and milestones.
 - ✅ Fixed reset handler scope for convert tabs
 - ✅ Restored 25%/33%/50%/75% target size reduction presets
 - ✅ Default bitrate preset set to 2.5 Mbps and added 2.0 Mbps option
+- ✅ Default encoder preset set to slow
 - ✅ Stabilized video seeking and embedded rendering
 - ✅ Improved player window positioning
 - ✅ Fixed clear video functionality
diff --git a/TODO.md b/TODO.md
index 1a1f989..cf653fd 100644
--- a/TODO.md
+++ b/TODO.md
@@ -56,6 +56,7 @@ This file tracks upcoming features, improvements, and known issues.
   - Reset handler scope fixed for convert tabs
   - Target size reduction presets restored (25/33/50/75%)
   - Default bitrate preset set to 2.5 Mbps with added 2.0 Mbps option
+  - Default encoder preset set to slow
 
 *Last Updated: 2025-12-20*
 
diff --git a/main.go b/main.go
index 10935fc..91b2190 100644
--- a/main.go
+++ b/main.go
@@ -515,7 +515,7 @@ func defaultConvertConfig() convertConfig {
 		AutoNameTemplate: "<actress> - <studio> - <scene>",
 
 		VideoCodec:             "H.264",
-		EncoderPreset:          "medium",
+		EncoderPreset:          "slow",
 		CRF:                    "",
 		BitrateMode:            "CRF",
 		BitratePreset:          "2.5 Mbps - Medium Quality",