The XIPS Challenge – how fast does Excel calculate?

It used to be fashionable to measure computer speed in MIPS (millions of instructions per second).
So I thought it would be interesting to:

  • Find out how many XIPS (Excel Calculations per second) Excel could do on a modern PC.
  • Then challenge people to guess how many calculations per second they thought Excel could do.

For my test I used Excel 2010 on my desktop PC, which is currently an Intel I7 870 2.93 GHz. This PC has 4 cores each of which can run 2 threads, so Excel 2010 could run 8 calculation threads in parallel if I set up the test properly.

In row 1 I entered =RAND() and copied the formula across to column Z.
Then I entered =A1+1 into A2 and copied the formula across to column Z, and then down to row 256000.
this gave me 6656000 formulae (6.6 million) in 26 independent calculation chains.

Then I switched to Manual Calculation mode and pressed F9 or Ctrl/AltF9 a few times to time the calculation (I was using FastExcel to time the calculations, if you don’t own FastExcel you can find the code for a simple calculation timer in my MSDN article on finding and prioritizing Excel Calculation Bottlenecks ).

OK, so how many XIPS do YOU think Excel can do?

  • 1000 per second?
  • 10000 per second?
  • 100000 per second?
  • 1000000 per second?
  • More than 1000000 per second?

My PC calculated the 6.6 million formulae in under a second (the average was about 0.96), so my PC is rated at 6.9 MXIPS (millions of Excel calculations per second).

Well I know its very simple formulae but WOW!!!

I was giving a talk a couple of years ago at the London Excel Users Conference on Improving Excel Performance, and I asked the audience the XIPS question: most of them thought the answer was in the tens or hundreds of thousands: nobody thought it was over a million.

So here is a question for future posts:

If Excel can calculate formulae this fast how come my spreadsheet takes several seconds to calculate?

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3 Responses to The XIPS Challenge – how fast does Excel calculate?

  1. ross says:

    Great stuff Charles, looking forward to the answer in part 2.
    Ross

  2. “If Excel can calculate formulae this fast how come my spreadsheet takes several seconds to calculate?”

    That’s a conundrum that’s earned me a very comfortable living for a good few years now, and I’m sure I don’t have anywhere near all the reasons, so I’m looking forward to seeing some things I’ve missed!

    • fastexcel says:

      Kanwaljit, Hopefully the answers are worth more than the question!
      Ross, Hopefully there will be many Part2s …
      Mike, I am sure i don’t have all the answers either .

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