diff --git a/AUDIT.md b/AUDIT.md
index e89606b..b34b55e 100644
--- a/AUDIT.md
+++ b/AUDIT.md
@@ -25,7 +25,11 @@ Target: Turtle WoW 1.18.x / Octo client.
 
 ## Fixed in 1.4.9
 
-- **Missing `Open Mail` button:** upstream creates `TurtleMailOpenMailButton` only once in `inbox_load()` and assumes it will remain parented, positioned, and visible forever. If that creation path is interrupted or another mailbox/UI addon hides or re-parents the button, TurtleMail never recovers it. The compatibility layer now uses an idempotent inbox loader and an `ensure_open_mail_button()` recovery path that recreates the button if needed, restores its parent/anchor/text/click handler/frame level, and re-shows it on mailbox/inbox refreshes.
+- **Missing `Open Mail` button:** upstream creates `TurtleMailOpenMailButton` only once in `inbox_load()` and assumes it will remain parented, positioned, and visible forever. If that creation path is interrupted or another mailbox/UI addon hides or re-parents the button, TurtleMail never recovers it. The compatibility layer now uses an idempotent inbox loader and an `ensure_open_mail_button()` recovery path that recreates the button if needed and restores its parent/anchor/text/click handler/frame level.
+
+## Fixed in 1.4.10
+
+- **First mailbox-open freeze/stutter after the 1.4.9 recovery fix:** 1.4.9 called `ensure_open_mail_button()` on every `MAIL_INBOX_UPDATE`. Initial inbox population can emit a burst of those events, so the button was repeatedly re-parented, re-anchored, re-labeled, resized, and given a new frame level. 1.4.10 removes that work from `MAIL_INBOX_UPDATE` and makes `ensure_open_mail_button()` state-aware, so it only mutates the UI when the button is missing, hidden, moved, re-parented, or otherwise incorrect.
 
 ## Remaining architectural risks upstream
 
@@ -48,4 +52,4 @@ The compatibility build was tested in-game on Turtle WoW 1.18.x and the reported
 
 ## Status
 
-**1.4.9 is the current stable release.** The fixes remain isolated in `TurtleMailFix.lua` so upstream code stays easy to compare and future upstream changes remain easier to merge.
+**1.4.10 is the current stable release.** The fixes remain isolated in `TurtleMailFix.lua` so upstream code stays easy to compare and future upstream changes remain easier to merge.
diff --git a/README.md b/README.md
index 0639506..86df378 100644
--- a/README.md
+++ b/README.md
@@ -76,7 +76,7 @@ When enabled, TurtleMail records sent and received mail information in its dedic
 
 ## 🔧 Turtle WoW compatibility
 
-Version **1.4.9** extends the compatibility and safety layer for Turtle WoW 1.18.x environments.
+Version **1.4.10** extends the compatibility and safety layer for Turtle WoW 1.18.x environments.
 
 The compatibility work is isolated in `TurtleMailFix.lua` so the original TurtleMail code remains easier to compare with upstream versions.
 
@@ -96,7 +96,8 @@ The compatibility work is isolated in `TurtleMailFix.lua` so the original Turtle
 - Rebound the safer `OnUpdate` handler correctly after loading the compatibility layer.
 - Prevented the send queue from remaining stuck when an attachment becomes unavailable during sending.
 - Fixed `MailMailButton` nil crashes while enabling/disabling or clearing the send form, and hardened the paired subject edit-box reference.
-- Restored the missing **Open Mail** button by making its creation idempotent and reasserting its parent, position, visibility, click handler, and frame level when the mailbox refreshes.
+- Restored the missing **Open Mail** button with an idempotent recovery path.
+- Reduced first-open mailbox stutter by removing Open Mail layout repair from `MAIL_INBOX_UPDATE` and only changing the button when its state is actually wrong.
 
 The complete technical audit is available in [`AUDIT.md`](AUDIT.md).
 
@@ -131,11 +132,11 @@ TurtleMail includes localization support for:
 
 Current stable version:
 
-**1.4.9**
+**1.4.10**
 
 Based on upstream **TurtleMail 1.4.5**.
 
-Version 1.4.9 adds recovery for the **Open Mail** inbox button when its initial creation is interrupted or another UI addon hides/re-parents it. The earlier compatibility fixes remain unchanged.
+Version 1.4.10 keeps the **Open Mail** recovery from 1.4.9 but makes it lightweight: the button is repaired on load/mailbox open only when needed, instead of being re-parented and re-anchored on every inbox refresh. This avoids repeated layout work during the initial mailbox update burst.
 
 ## 🖼️ Screenshots
 
diff --git a/TurtleMail.toc b/TurtleMail.toc
index 7f0294d..2f6bbde 100644
--- a/TurtleMail.toc
+++ b/TurtleMail.toc
@@ -2,7 +2,7 @@
 ## Interface: 11200
 ## Title: |cffabd473Turtle|cffffffffMail
 ## Author: shirsig/sica, Dusk-92 (compatibility fixes)
-## Version: 1.4.9
+## Version: 1.4.10
 ## Notes: Mailbox enhancement - Turtle WoW 1.18.x compatibility
 ## SavedVariables: TurtleMail_AutoCompleteNames
 ## SavedVariablesPerCharacter: TurtleMail_To TurtleMail_Point TurtleMail_Log
diff --git a/TurtleMailFix.lua b/TurtleMailFix.lua
index 032332c..65d032d 100644
--- a/TurtleMailFix.lua
+++ b/TurtleMailFix.lua
@@ -8,7 +8,7 @@ local m = TurtleMail
 local getn = table.getn
 local function pack( ... ) return arg end
 
-m.compat_version = "1.4.9"
+m.compat_version = "1.4.10"
 
 local DEFAULT_SENT_FILTERS = {
   Money = 1,
@@ -181,40 +181,92 @@ end
 
 -- The upstream Open Mail button is created only once in inbox_load(). If that
 -- creation is skipped/interrupted, or another UI addon hides/re-parents the
--- button afterwards, TurtleMail never recreates it. Keep the button recoverable
--- whenever the mailbox/inbox is shown or refreshed.
+-- button afterwards, TurtleMail never recreates it. Keep the button recoverable,
+-- but only mutate its layout when something is actually wrong. This avoids doing
+-- repeated SetParent/ClearAllPoints/SetPoint work during inbox refresh bursts.
 local function ensure_open_mail_button()
   local inbox = m.api.InboxFrame
   if not inbox or not m.api.CreateFrame then return nil end
 
   local button = m.api.TurtleMailOpenMailButton
+  local created = false
   if not button or type( button.SetPoint ) ~= "function" then
     button = m.api.CreateFrame( "Button", "TurtleMailOpenMailButton", inbox, "UIPanelButtonTemplate" )
     m.api.TurtleMailOpenMailButton = button
+    created = true
   end
 
-  if button.SetParent then button:SetParent( inbox ) end
-  if button.ClearAllPoints then button:ClearAllPoints() end
-  button:SetPoint( "BOTTOM", inbox, "BOTTOM", -10, 90 )
-
-  if button.SetText then button:SetText( m.api.OPENMAIL or "Open Mail" ) end
-
-  local width = 120
-  local font_string = button.GetFontString and button:GetFontString()
-  if font_string and font_string.GetStringWidth then
-    width = math.max( 120, 30 + (font_string:GetStringWidth() or 0) )
+  local parent_changed = false
+  if button.GetParent and button.SetParent then
+    if button:GetParent() ~= inbox then
+      button:SetParent( inbox )
+      parent_changed = true
+    end
+  elseif created and button.SetParent then
+    button:SetParent( inbox )
+    parent_changed = true
   end
 
-  if button.SetWidth then button:SetWidth( width ) end
-  if button.SetHeight then button:SetHeight( 25 ) end
-  if button.SetScript then button:SetScript( "OnClick", m.inbox_open_all ) end
+  local needs_anchor = created or parent_changed
+  if not needs_anchor and button.GetPoint then
+    local point, relative_to, relative_point, x, y = button:GetPoint()
+    needs_anchor = point ~= "BOTTOM"
+      or (relative_to and relative_to ~= inbox)
+      or relative_point ~= "BOTTOM"
+      or x ~= -10
+      or y ~= 90
+  end
+
+  if needs_anchor then
+    if button.ClearAllPoints then button:ClearAllPoints() end
+    button:SetPoint( "BOTTOM", inbox, "BOTTOM", -10, 90 )
+  end
+
+  local wanted_text = m.api.OPENMAIL or "Open Mail"
+  local text_changed = created
+  if button.GetText then
+    text_changed = button:GetText() ~= wanted_text
+  end
+  if text_changed and button.SetText then
+    button:SetText( wanted_text )
+  end
+
+  -- Recalculate dimensions only when the button was created or its label changed.
+  if created or text_changed then
+    local width = 120
+    local font_string = button.GetFontString and button:GetFontString()
+    if font_string and font_string.GetStringWidth then
+      width = math.max( 120, 30 + (font_string:GetStringWidth() or 0) )
+    end
+    if button.SetWidth then button:SetWidth( width ) end
+    if button.SetHeight then button:SetHeight( 25 ) end
+  end
+
+  if button.SetScript then
+    local onclick = button.GetScript and button:GetScript( "OnClick" ) or nil
+    if created or onclick ~= m.inbox_open_all then
+      button:SetScript( "OnClick", m.inbox_open_all )
+    end
+  end
 
   if inbox.GetFrameLevel and button.SetFrameLevel then
-    button:SetFrameLevel( (inbox:GetFrameLevel() or 0) + 5 )
+    local target_level = (inbox:GetFrameLevel() or 0) + 5
+    local current_level = button.GetFrameLevel and button:GetFrameLevel() or nil
+    if current_level ~= target_level then
+      button:SetFrameLevel( target_level )
+    end
   end
 
-  if button.Enable then button:Enable() end
-  if button.Show then button:Show() end
+  if button.Enable then
+    if not button.IsEnabled or not button:IsEnabled() then
+      button:Enable()
+    end
+  end
+  if button.Show then
+    if not button.IsShown or not button:IsShown() then
+      button:Show()
+    end
+  end
   return button
 end
 
@@ -530,8 +582,6 @@ end
 
 -- Hide stale AH/returned icons on rows that no longer contain mail.
 function m.MAIL_INBOX_UPDATE()
-  ensure_open_mail_button()
-
   if m.inbox_opening then
     m.inbox_update = true
   end