Outlook, Word, Excel, PowerPoint, and OneNote have already been upgraded to support Apple Silicon, or rather the M1 chip in Air, Pro and mini. The same is Firefox.
The office package is now Universal Apps that supports both Intel and Apple Silicon
This will help with performance as Rosetta 2 does not have to be involved. That said, we've been using Office on an M1 MacBook Air 8GB for several weeks and have never experienced performance issues, but now it's even better. It is already the case that Rosetta 2 runs Windows faster than Surface Pro X.
One of the great benefits of Apple's ARM approach on Mac is the efficient Rosetta 2 Translator, which is far faster than traditional emulation.
Firefox also updated with Apple Silicon support
Firefox was also updated and starts over 2.5 times faster - web apps are now twice as responsive in terms of interface and usage, reports Mozilla.
Note that you will need to quit Firefox completely to start the M1 version. Note that this is the same version that is the very latest with Adobe Flash support.
Read our test of the MacBook M1 8GB: