Upgraded from 2007 to 365 and my VBA runs much, much slower.

I finally got around to upgrading from ver. 2007 to 365 as I know 2007 is no longer supported by MS and I've been told that there have been a ton of feature and performance improvements besides.

But my working .xlsm file, particularly the macros, are incredibly laggy. Yes it's a large file (17MB) that pulls in real-time data for hundreds of stock symbols and runs a bunch of calculations and conditional formatting in the background, but performance in 2007 was at least alright, whereas it's borderline unusable when opened in the new 365 Excel. Just one example: I have a simple listbox and a mouse macro to cycle through the ~20 listbox items...it took approx 1/4 of a second to cycle to the next listbox item with a mouse click in 2007. It's closer to 1.25s (5x slower) in 365.

Was alarmed that performance was so much worse in a 12-year newer version...

• Is this a known performance issue...? Like, is there something about how 365 handles calculations or VBA or conditional formatting that's dramatically different than in previous versions?
• What options can I toggle in 365 in hopes of either improvement performance or at least troubleshooting? So far, I've:
  1. Options...Ease of Access...Unchecked "Provide Feedback with Animation", since I found the default "glide" / animation effect annoying
  2. Options...Advanced...Checked "DIsable Hardware Graphics Acceleration", since online reading suggested that disabling it could improve performance but I didn't notice anything.
• Tried the 32-bit version of 365 since I'd read that might help even if your system is 64-bit...performance seems the same to me :/
• Something I wondered: would recreating this file as a native 365 file starting with a blank 365 .xlsm workbook result in better performance? IOW, I created this starting from a blank 2007 Workbook, and while obviously 365 is backwards compatible with .xlsm files created in previous versions, is there something about a native-to-365 .xlsm file that would, for some reason, result in better performance?

EDITING post at request of an admin because I made a similar post on a different forum, but received no help, which is why I came here hoping for some from the sleuths on this forum.