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

I have been experiencing LOTS of performance issues lately, RAM going to around 5GBs for just two 3MB files opened.

Then today Copilot showed a suggestion and it hit me, COPILOT IS THE ISSUE.

went to disable it:

1. Open Excel and click File in the top left corner.

2. Select Options at the bottom of the left menu.

3. Select Copilot in the left-hand pane.

4. Clear the "Enable Copilot" checkbox.

5. Select OK, then close and restart Excel.

And NOW I can work normally as I used to.

Hope this helps, it has helped me.