By Laura Holzwarth

Performance issues are some of our biggest call generators. Users get frustrated with Excel when they upgrade to later versions. Performance issues often boil down to spreadsheets that have been around a long time and the design. Here are some of the common problem areas:

Slow Opening: Opening an Excel file the first time may be slow if you have a large number of calculations.  Excel needs to recalculate the file and verify the values in the workbook.  See KB’s below for more information.  

210162 - Workbook loads slowly the first time that it is opened in Excel
http://support.microsoft.com/kb/210162/en-us

925893 - External links may be updated in Excel 2007 when you open a workbook that was last saved in an earlier version of Excel
http://support.microsoft.com/kb/925893/en-us

Updated Add-ins: Check your third party add-in companies to make sure you are using the latest version of the add-in.  All too often the code in the add-ins has changed and the newer add-in
will run much better.

Formulas: Formulas referencing entire columns might display poor performance in .xlsx files.  The grid size has grown from 65,536 to 1,048,576 rows and 256 (IV) to 16,384 (XFD) columns.  A popular (not a best practice) way to create formulas was to reference entire columns.

For instance if you have a VLOOKUP that looked like this: 

=VLOOKUP(A1,$D:$M,2,FALSE)

In Excel 2003 and prior it was referencing 655,560 cells (10 columns x 65,536 rows). With the new bigger grid, this same formula is referencing over 10 million cells.  (10 columns x 1,048,576 rows = 10,485,760).

Shapes: When copy and pasting data from various locations, such as websites and other applications, hidden objects can be copied into the Excel file.  These objects can cause performance issues in the preadsheet.
To determine if you have shapes in the file turn on Selection Pane. 

On the Home Ribbon choose, Find and Select, Selection Pane to display a list of all shapes in the worksheet. You can pick and choose to delete the shapes by selecting the shapes and deleting
them.  If you want to delete all shapes on the sheet, press Ctrl-G, choose Special, and then choose Objects. This will highlight all shapes and then you can delete them.

Defined Names: Check for any defined names linking to other workbooks or temporary internet files. Typically these links are unnecessary to the workbook, and slow down the opening of the Excel file.  You can use these tools to see hidden defined names that we can’t see in the Excel interface.

http://www.jkp-ads.com/officemarketplacenm-en.asp

Styles: Old Excel files may collect styles and make the file grow.  For more information see http://support.microsoft.com/kb/213904 and clean out the file of excess styles use the following tool.

 Style Cleaner Tool

Excess file format cleaner:  If files have been formatted by highlighting entire columns the file will grow in size rapidly.  We also occasionally see this problem when copying or importing data from web pages or
databases.  To clean up excess formatting use the Excess Format cleaner found there http://xsformatcleaner.codeplex.com/ for more information see the following KB

How to reset the last cell in Excel

http://support.microsoft.com/kb/244435

Personal.xls: If you are using a personal macro template located in the XLStart Folder, you will want to make sure that you open it in the latest version of Excel, do a full calculation, and save it as a personal.xlsx. You will only have to do this once.  If you don’t do this, it calculates each time you open Excel, slowing down the open process.

XLSB extension:  If you have large files that take a long time to open (after their first calculate and save –number 1 in this list), try saving the file with an .xlsb extension.  Saving with this binary format will make the
file smaller and the load times faster.  See the following article for more information about the new file formats: http://blogs.office.com/b/microsoft-excel/archive/2006/07/20/all-about-file-formats.aspx.

Macros and VBA: If you have a macro that worked until Excel 2010, check out the following link for the Object Model changes: http://msdn.microsoft.com/en-us/library/ee836187.aspx

There certainly could be more issues that can affect performance issues in Excel, but these are the most common. If you are looking for more information about how to improve performance in Excel, see the
following MSDN article: http://msdn.microsoft.com/en-us/library/aa730921(v=office.12).aspx