Fix for issue 2349

src/EPPlus/ExcelPackageAsync.cs

@@ -175,8 +175,8 @@ private async Task LoadAsync(Stream input, Stream output, string Password, Cance
 				}
                 finally
                 {
-                    ms.Dispose();
-				}
+                    //ms.Dispose();   //Don't dispose the stream as it is used as the base for the ZipPackage when having 2GB streams or larger. It will be disposed when the package is disposed or saved.
+                }
             }
             //Clear the workbook so that it gets reinitialized next time
             this._workbook = null;

src/EPPlusTest/Longrunning Tests/LongRunningTests.cs

@@ -159,6 +159,47 @@ public void PerformanceIssueGetAsByteArray()
                 SaveWorkbook("PivotTest_calculated_columns.xlsx", p);
             }
         }
+        [TestMethod]
+        public void PerformanceIssueLoadAndSave()
+        {
+            using (var p = OpenTemplatePackage("LargeWorkbookTemplate.xlsx"))
+            {
+                /* Raw Data Sheet only */
+                ExcelWorksheet ws = p.Workbook.Worksheets[0];  // second sheet
+
+                p.Workbook.Calculate();
+                SaveWorkbook("LargeWBSave.xlsx", p);
+            }
+        }
+        [TestMethod]
+        public void PerformanceIssueLoadAndSaveSync()
+        {
+            using (var p = new ExcelPackage())
+            {
+                var file = GetTemplateFile("LargeWorkbookTemplate.xlsx");
+                p.Load(new FileStream(file.FullName, FileMode.Open));
+                /* Raw Data Sheet only */
+                ExcelWorksheet ws = p.Workbook.Worksheets[0];  // second sheet
+
+                p.Workbook.Calculate();
+            }
+        }
+
+
+        [TestMethod]
+        public async Task PerformanceIssueLoadAndSaveAsync()
+        {
+            using (var p = new ExcelPackage())
+            {
+                var file = GetTemplateFile("LargeWorkbookTemplate.xlsx");
+                await p.LoadAsync(file);
+                /* Raw Data Sheet only */
+                ExcelWorksheet ws = p.Workbook.Worksheets[0];  // second sheet
+
+                p.Workbook.Calculate();                
+            }
+        }
+
         #endregion
         #region HtmlExport
         [TestMethod]