diff --git a/base b/base
index 7b05d5a73..9ba142825 160000
--- a/base
+++ b/base
@@ -1 +1 @@
-Subproject commit 7b05d5a73980f852290e3f10e6078cc88162bbea
+Subproject commit 9ba142825282b44446d09985669022ac9e3ba64e
diff --git a/frontend/apps/reader/modules/readerrolling.lua b/frontend/apps/reader/modules/readerrolling.lua
index 1634b7ea4..2790c358f 100644
--- a/frontend/apps/reader/modules/readerrolling.lua
+++ b/frontend/apps/reader/modules/readerrolling.lua
@@ -1203,6 +1203,12 @@ function ReaderRolling:checkXPointersAndProposeDOMVersionUpgrade()
 
         -- Set latest DOM version, to be used at next load
         local latest_dom_version = self.ui.document:getLatestDomVersion()
+        -- For some formats, DOM version 20200824 uses a new HTML parser that may build
+        -- a different DOM tree. So, migrate these to a lower version
+        local doc_format = self.ui.document:getDocumentFormat()
+        if doc_format == "HTML" or doc_format == "CHM" or doc_format == "PDB" then
+            latest_dom_version = self.ui.document:getDomVersionWithNormalizedXPointers()
+        end
         self.ui.doc_settings:saveSetting("cre_dom_version", latest_dom_version)
         logger.info("  cre_dom_version updated to", latest_dom_version)
 
diff --git a/frontend/apps/reader/readerui.lua b/frontend/apps/reader/readerui.lua
index 6ee85fa40..8d68382ba 100644
--- a/frontend/apps/reader/readerui.lua
+++ b/frontend/apps/reader/readerui.lua
@@ -53,6 +53,7 @@ local ReaderZooming = require("apps/reader/modules/readerzooming")
 local Screenshoter = require("ui/widget/screenshoter")
 local SettingsMigration = require("ui/data/settings_migration")
 local UIManager = require("ui/uimanager")
+local ffiUtil  = require("ffi/util")
 local lfs = require("libs/libkoreader-lfs")
 local logger = require("logger")
 local util = require("util")
@@ -270,15 +271,22 @@ function ReaderUI:init()
         end
         -- make sure we render document first before calling any callback
         self:registerPostInitCallback(function()
+            local start_ts = ffiUtil.getTimestamp()
             if not self.document:loadDocument() then
                 self:dealWithLoadDocumentFailure()
             end
+            logger.dbg(string.format("  loading took %.3f seconds", ffiUtil.getDuration(start_ts)))
 
             -- used to read additional settings after the document has been
             -- loaded (but not rendered yet)
             self:handleEvent(Event:new("PreRenderDocument", self.doc_settings))
 
+            start_ts = ffiUtil.getTimestamp()
             self.document:render()
+            logger.dbg(string.format("  rendering took %.3f seconds", ffiUtil.getDuration(start_ts)))
+
+            -- Uncomment to output the built DOM (for debugging)
+            -- logger.dbg(self.document:getHTMLFromXPointer(".0", 0x6830))
         end)
         -- styletweak controller (must be before typeset controller)
         self:registerModule("styletweak", ReaderStyleTweak:new{
diff --git a/frontend/document/credocument.lua b/frontend/document/credocument.lua
index 17b28b84f..32cc2aa34 100644
--- a/frontend/document/credocument.lua
+++ b/frontend/document/credocument.lua
@@ -180,6 +180,10 @@ function CreDocument:requestDomVersion(version)
     cre.requestDomVersion(version)
 end
 
+function CreDocument:getDocumentFormat()
+    return self._document:getDocumentFormat()
+end
+
 function CreDocument:setupDefaultView()
     if self.loaded then
         -- Don't apply defaults if the document has already been loaded