Excel 365 is UNUSABLE for professional work — performance has catastrophically degraded

You've included a lot of good details and have tried quite a few solutions already.

One thing you have not yet included is a typical sample workbook with anonymized data. I understand you may not want to upload a workbook with confidential information and anonymizing the data can be a chore.  My suggestion: run Inquire's Workbook Analysis to audit a workbook and share the .xlsx here.  This will provide an extensive report about the workbook but not include the data.

— Moving a simple shape (a circled number annotation) across a worksheet takes SECONDS. This is not a complex object. It is a circle with a number in it.

— Scrolling is laggy and jerky, even on sheets with minimal data.

— Pressing ALT to activate ribbon shortcuts has a delay so severe that subsequent keystrokes are DROPPED. I have to sit and wait for your UI to catch up before I can use keyboard shortcuts I've relied on for over a decade.

— Selecting and editing cells is noticeably slower than it was two years ago.

— Interacting with comments is painfully slow.

— Chart objects are sluggish to select, move, or resize.

These are classic rendering issues.  Others have already suggested checking the selection pane for object count (or use the immediate window).  The entire workbook can be combed to check this pane for each sheet.  It only takes 1 sheet with a few thousand objects to slow the navigation.

I do use OFFSET, INDEX/MATCH, among others.

OFFSET is best avoided in 365 because there are better options.  INDEX/MATCH can usually be done with XLOOKUP.  A full audit of a workbook with Inquire will list all the formulas in a workbook and give us an idea of how your workbook is setup.

Hi RIM_LLC,

I want to add my voice here to validate your assessment. You have clearly done an exhaustive job troubleshooting—rolling back builds, Safe Mode, and stripping out add-ins are the definitive steps to prove this is not a local issue.

I also want to acknowledge the suggestions from m_tarler and Detlef_Lewin. Their advice is technically correct for standard corruption or calculation bottlenecks, and your responses have demonstrated that your scenario goes beyond that into a platform-level regression regarding how Excel 365 handles GDI+ objects (shapes/charts) in the new Fluent UI rendering pipeline.

Since waiting for Microsoft to fix this could take months, here are two "escape hatches" that I have seen power users deploy to bypass the current rendering bug without abandoning their workbooks:

 1. The "Hybrid Rendering" Workaround

There is a known, if undocumented, quirk where Excel for the Web uses a different rendering layer than the Desktop App. You can sometimes force the Desktop App to "inherit" the lighter web-based rendering state:

• Upload your workbook to OneDrive or SharePoint
• Open it in Excel for the Web (in your browser)
• Click Edit Workbook > Open in Desktop App

This often forces the desktop instance to initialize using a legacy compatibility view for the UI shell (the same rendering path used for older file formats), temporarily bypassing the DirectX/GDI+ lag that affects shapes, charts, and the ALT key. It is not permanent—the state resets when you close—but it can restore responsiveness for a critical session.

 2. The "Dark Mode" Transparency Test

You mentioned using a dark background, which is essential for long hours. The current Fluent UI has a known issue with how it handles "Acrylic" and "Mica" transparency effects—these shaders can create a memory leak when rendering dark shapes over dark grids, particularly with GPU-accelerated rendering.

Test this:

• Go to File > Options > General
• Temporarily switch the Office Theme to "White" or "Light Gray"
• Keep your cell backgrounds dark (that setting is independent)

The logic: If performance returns, we have isolated the cause to the transparency shader layer interacting with your shapes and charts. This won't solve the root cause, but it may offer a usable workaround until they patch it.

I hope these workarounds give you a path forward.

The picture related to the reply above:

[THIRD TRY TO REPLY - WEBSITE WILL NOT REGISTER; TRYING WITHOUT PICTURE]

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).

One overall point: I have been working with the same template for, literally, 20 years, between 8 and 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 nor 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.

Here is what I have already tried — NONE of it helped:

What is the number of objects (shapes, charts, pictures, icons, etc.) in your sheet?

Take a look at the selection pane.

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.