Excel Office 365 2016 So Slow that I cannot use it

I've found a solution that works for me, though it is somewhat labor intensive it does solve the issue as far as I can tell.

I was previously on Office 2010 and upgraded to 365. Every single legacy excel sheet I had suffered from severe lag when doing regular, mundane tasks like copy and pasting, inserting columns, inputting numbers... things that should never lag. I have an i5-8250U, 8gb ram, 256gb SSD, and MX150, not the most powerful pc but brand new and more than enough to handle Excel.

I tried clearing all formats, links, named ranges, macros, etc. I uninstalled all my add-ons. I tried turning off hardware acceleration. I upgraded to 64 bit. None of these things worked for me. 

Finally, I simply opened a new workbook, I selected all the cells on the sheet with CTRL + A, and then I cut and pasted them into the new workbook. Boom. problem solved. You can rinse and repeat this process for each sheet in your workbook into the new workbook and the problem is fixed (as far as I can tell). Yes this is a tedious process but it worked for me.

Somebody please explain why the h*** a workbook that used to run on 50-75mb of ram in 2010 is eating up almost 500mb of ram in 2016? 

It has become so unbearably slow that I feel like throwing my laptop through the fkn window at times.

Not a solution I'm afraid, but my similar problem since installing 365 a week ago is that everything runs slowly, including my Thunderbird e-mail, Publisher, Word and I haven't even tried Excel. When not running slowly I get a Not Responding message. Somebody remind me what the advantages are of Office 365... So far it appears to be a total crock.

I'm sorry to hear that you all are encountering these performance issues.  A couple of questions.

First question: are you experiencing this on all workbooks or just on some?  If on some, are you filtering on that workbook?

Second question: Are you using the 32 bit or 64 bit version of office?

Third question: Are you using Win10?  If so you might have a bad video driver which could affect a number of functions within Excel.  To determine if this is indeed the case, please do the following and see if you still encounter the issue:

1.Boot Microsoft Excel

2.Click File > Options > Advanced.

3.Under Display, turn on the "Disable hardware graphics acceleration" check box.

4.Quit Excel

5.Re-boot Excel

If the video driver was the issue you shouldn't see the problem anymore.

If that does solve the issue, re-enable the setting and then go to the following post to see how to update your driver:

http://answers.microsoft.com/en-us/office/forum/office\_2016-word/fixed-11516-excel-word-or-outlook-problems-caused/6305c25e-b855-4621-8936-978f0d5dec91

Bob Archer

Microsoft Excel Team

Bob your a life saver I have tried every option under the sun and none worked Guess what yours did it was the graphics driver slowing every thing down now it is lightning fast I will see if I can get an updated driver from DELL hope I don't have any other problem because I have switch ed it off !!!!!!!!!!!!!!! Wonderful

Nothing fancy I'm afraid. I just applied the conditional formatting to a specific range of cells in the relevant columns. For example, I currently have about a thousand rows populated with data in one workbook and instead of applying the formatting to over 100k cells in the whole columns I applied it to the existing populated cells plus a bit more (1200), extending this as necessary as I add more data.

Maybe not the best solution, but at least I can now use my workbook without having to curse the previous long and unacceptable delays.