diff --git a/PowerEditor/src/Parameters.cpp b/PowerEditor/src/Parameters.cpp
index 7436c2c3b..f26b20fab 100644
--- a/PowerEditor/src/Parameters.cpp
+++ b/PowerEditor/src/Parameters.cpp
@@ -2025,6 +2025,9 @@ bool NppParameters::getSessionFromXmlTree(TiXmlDocument *pSessionDoc, Session *p
 					mapPosStr = (childNode->ToElement())->Attribute(TEXT("mapHeight"), &mapPosVal);
 					if (mapPosStr)
 						mapPosition._height = mapPosVal;
+					mapPosStr = (childNode->ToElement())->Attribute(TEXT("mapKByteInDoc"), &mapPosVal);
+					if (mapPosStr)
+						mapPosition._KByteInDoc = mapPosVal;
 					mapPosStr = (childNode->ToElement())->Attribute(TEXT("mapWrapIndentMode"), &mapPosVal);
 					if (mapPosStr)
 						mapPosition._wrapIndentMode = mapPosVal;
@@ -2979,6 +2982,7 @@ void NppParameters::writeSession(const Session & session, const TCHAR *fileName)
 				(fileNameNode->ToElement())->SetAttribute(TEXT("mapHigherPos"), viewSessionFiles[i]._mapPos._higherPos);
 				(fileNameNode->ToElement())->SetAttribute(TEXT("mapWidth"), viewSessionFiles[i]._mapPos._width);
 				(fileNameNode->ToElement())->SetAttribute(TEXT("mapHeight"), viewSessionFiles[i]._mapPos._height);
+				(fileNameNode->ToElement())->SetAttribute(TEXT("mapKByteInDoc"), static_cast<int>(viewSessionFiles[i]._mapPos._KByteInDoc));
 				(fileNameNode->ToElement())->SetAttribute(TEXT("mapWrapIndentMode"), viewSessionFiles[i]._mapPos._wrapIndentMode);
 				fileNameNode->ToElement()->SetAttribute(TEXT("mapIsWrap"), viewSessionFiles[i]._mapPos._isWrap ? TEXT("yes") : TEXT("no"));
 
diff --git a/PowerEditor/src/Parameters.h b/PowerEditor/src/Parameters.h
index 194b0061e..441e912ad 100644
--- a/PowerEditor/src/Parameters.h
+++ b/PowerEditor/src/Parameters.h
@@ -149,8 +149,15 @@ struct MapPosition
 	int32_t _width = -1;
 	int32_t _height = -1;
 	int32_t _wrapIndentMode = -1;
+
+	int64_t _KByteInDoc = _maxPeekLenInKB;
+
 	bool _isWrap = false;
-	bool isValid() { return _firstVisibleDisplayLine != -1; };
+	bool isValid() const { return (_firstVisibleDisplayLine != -1); };
+	bool canScroll() const { return (_KByteInDoc < _maxPeekLenInKB); }; // _nbCharInDoc < _maxPeekLen : Don't scroll the document for the performance issue
+
+private:
+	int64_t _maxPeekLenInKB = 512; // 512 KB
 };
 
 
diff --git a/PowerEditor/src/WinControls/DocumentMap/documentSnapshot.cpp b/PowerEditor/src/WinControls/DocumentMap/documentSnapshot.cpp
index a071d8958..687ed700d 100644
--- a/PowerEditor/src/WinControls/DocumentMap/documentSnapshot.cpp
+++ b/PowerEditor/src/WinControls/DocumentMap/documentSnapshot.cpp
@@ -68,6 +68,7 @@ void DocumentPeeker::goTo(POINT p)
 	::SetWindowPos(_hSelf, HWND_TOP, p.x, p.y + 10, _rc.right - _rc.left, _rc.bottom - _rc.top, SWP_SHOWWINDOW);
 }
 
+
 void DocumentPeeker::syncDisplay(Buffer *buf, ScintillaEditView & scintSource)
 {
 	if (_pPeekerView)
@@ -85,8 +86,10 @@ void DocumentPeeker::syncDisplay(Buffer *buf, ScintillaEditView & scintSource)
 		// Wraping & scrolling
 		//
 		MapPosition mp = buf->getMapPosition();
-		if (mp.isValid())
+		if (mp.isValid() && mp.canScroll())
+		{
 			scrollSnapshotWith(mp);
+		}
 
 		Buffer *buf = _pPeekerView->getCurrentBuffer();
 		_pPeekerView->defineDocType(buf->getLangType());
@@ -140,7 +143,7 @@ void DocumentPeeker::scrollSnapshotWith(const MapPosition & mapPos)
 		//
 
 		// scroll to the first visible display line
-		_pPeekerView->execute(SCI_LINESCROLL, 0,mapPos._firstVisibleDisplayLine);
+		_pPeekerView->execute(SCI_LINESCROLL, 0, mapPos._firstVisibleDisplayLine);
 		
 	}
 }
@@ -180,6 +183,9 @@ void DocumentPeeker::saveCurrentSnapshot(ScintillaEditView & editView)
 			mapPos._higherPos = static_cast<int32_t>(editView.execute(SCI_POSITIONFROMPOINT, 0, 0));
 		}
 
+		// Length of document
+		mapPos._KByteInDoc = editView.getCurrentDocLen() / 1024;
+
 		// set current map position in buffer
 		buffer->setMapPosition(mapPos);
 	}