Forum Discussion
Excel 365 is UNUSABLE for professional work — performance has catastrophically degraded
Hi RIM_LLC , The first thing you should know is that this is mostly a community forum where community members help other community members. Althogh some microsoft emplyees drop in here time to time this is not meant for nor the right place to report bugs or provide feedback to the microsoft Excel team. If you go into help and click on the feedback button or the contact support, that is where you might want to address some of these items.
That said, it is also possible it is your workbook that is having some issue either due to some calculations or corruption. Have you tried to run the Check Performance function (under the 'Review' tab)?
Also, have you tried changing from Automatic to Manual Calculations (under Calculations on the Formulas tab)?
Do you notice this issue with other workbooks? Have you tried copying the key formulas and pasting them into a new 'clean' workbook?
Some other considerations that should be investigated include making sure there are no circular references, bad external references/link/data, minimize the use of conditional formatting, minimize the use of volatile functions (for example the classic ones being: INDIRECT, OFFSET, RAND but can even be INDEX or others if they use abstracted ranges)
Another improvement you should consider is updating formulas to actually use the newer more optimized functions like XLOOKUP instead of LOOKUP. You also mention having 67 valuation models which I presume are complicated formulas and you might also find value in using LAMBDA functionality. A number of members here have posted excellent results using 'Thunks', which is a variant of using the LAMBDA function, to improve performance of various complicated formulas.
Finally please remember that myself and others here are just volunteers trying to help so although our answers may not be what you want to hear (i.e. we are not MicroSoft saying we are going to fix it), please note we are only trying to help.
Thank you, m_tarler and Detlef_Lewin, for the inputs. I'm very aware that this site is not an official Microsoft feedback site (I already posted the same complaint there - but I'm not expecting any response from them).
I also answered Detlef_Lewin's question yesterday, but for some reason the site didn't register it, so doing it again (this time writing on a notepad so I can copy-paste it until the site registers the response...)One overall point: I have been working with the same template for, literally, 20 years, between 8 to 12 hours a day. I'm not "new to Excel". Nor is this a problem with "one spreadsheet" - I'm having the same issue on all my spreadsheets on two machines. Excel was always a mediocre tool, but now it is unbearable to work with. My productivity is at 20% of its usual level.
So the questions/suggestions with my answers:
- What is the number of objects (shapes, charts, pictures, icons, etc.) in your sheet?
Not many - see the picture below. Pressing ALT+F10 (for those that might try the same) gave me the number of objects (on the right). If I try to drag Oval 39 with Line 36 (two very simple objects), Excel will blink, display a message that it is not responding, and, after some struggle, move the object.
- Have you tried to run the Check Performance function (under the 'Review' tab)?
My workbooks don't have incorrect calculations or corruption, as it is impossible for me to mess up with 70+ similar models. If I run Check Performance, it mostly complains about cell formatting (note on the picture below that my models have a dark background - it is impossible to work the hours I do with a bright-white screen)
- Have you tried changing from Automatic to Manual Calculations (under Calculations on the Formulas tab)?
All my models have manual calculations by default. Most valuation models (if you are trying to properly determine an adequate debt level) are circular, so I set them to manual mode to avoid wasting time on constant calculations.
- Do you notice this issue with other workbooks?
Yes - every single workbook has the same issue. Excel is slow with all of them, even relatively simple ones. And it is NOT my machine: I tested in two of them, turning off add-ins (I use FactSet, for instance), running Excel in Safe Mode, moving back to other releases (but maybe I will go back a few months, to see what happens). Nothing worked.
- Have you tried copying the key formulas and pasting them into a new 'clean' workbook?
See how many tabs I have in each model (in the picture below). It is basically impossible to copy and paste these models into other models. It would take me months to do so. And it would defeat the purpose of using Excel.
- Some other considerations that should be investigated include making sure there are no circular references, bad external references/link/data, minimize the use of conditional formatting, minimize the use of volatile functions
Circular references (as I discussed above) are inevitable. But again, I have been working with them for more than 20 years. I do use OFFSET, INDEX/MATCH, among others. But saying "don't use anything complex" defeats the purpose - in 2025 - of having powerful computers. I can't use Excel as a simple spreadsheet that performs addition, subtraction, multiplication, or division. If that is the case, I'd better investigate using Lotus 1-2-3! :) I will investigate the use of LAMBDA - it could make a few calculations more elegant.
I suspect that Microsoft is messing up with chart rendering. I say that because worksheets with charts scroll down very, very slowly. Maybe charts are being rendered constantly even when they are not shown. It could also explain the delay when I press ALT (not that the menus are hidden in the picture below - I don't use menus or toolbars, as I memorized all the keyboard shortcuts I need).
Last, thank you very much for taking the time to help me. Hopefully, I will find a solution. And maybe someone from Microsoft will see this thread and reach out.
