STILL NOTHING ! After couple of months ago, type here and on uservoice and beta versions program community. Report this issue to dev team. Nothing has changed...only two things:
1. I have added more ram from 16 to 72 to my iMac 2019 i9 3.6 ghz, 1TBSSD, Pro Vega 48 8GB
2. Bought Mac Book Pro maed out 16 inch with i9 2.4ghz, 1TB SSD, 64gb RAM, 5500 M 8GB 

and... the feeling and laggy illustrator is the same on both those machines. Nothing was improved. Still moving on cavas is laggy, still resizing rectanglem circle, triangle shapes are delayed. Where are more complex document, even the cursor on illustrator is delayed (feels like is drunk and its hard to point on anchor point or on the path).

Photoshop has improved and its really nice to work now but Illustrator is a disaster.

They could at least make the 76 unnecessary background processes and launch daemons run on a different cpu core to the application. Then the times that saving in the background doesn't fail, it wouldn't take 5x longer than a regular save used to.

And again, latest verson of AI for Mac. This is horrible mess of a software. I try to copy and paste vectors only into another file, and I'm stuck with spinning beachball half of the day. It's 2020, and Illustrator simply ain't capable of performing basic operations.

@Nikolas: And please do the same with photoshop: fresh code *halleluja

he means it's impossible with the pile of old code that illustrator is...
really adobe with what the programs cost to use and with a never ending money maker like the subscription model should have already rewritten the program from the ground up to be a modern application with fresh code.

How is this technically impossible?! Programs like Corel Draw and Affinity Designer are able to use multiple cpus and threads so I imagine Adobe can do it. The reason I imagine it’s taking so long is they’ll have to re-code a lot of the program from the ground up.

@Nebojša Kuzmanović: as was explained before – it probably is technically impossible to make the rendering of layered vectors a multithreaded task, because you can't parallelize the drawing of elements which overlay each other.
How should the lower layer estimate the shape of the layer above before it is calculated?

Under review more than 2 years?? Any updates on that?

If will this increase performance of Illustrator it will be cool but Adobe pls fix this issue from video underneath on macs:

https://youtu.be/HBO0pH_ee3A

Pls check this issue because is hard to work... I'm showing this problem from December 2019 but exist couploe of years... this is ridiculous...

Probably the most important thing for Adobe to sort out

This really need to be done. Especially in the time multiprocessing is going to be more and more.

TBH I love Illustrator embracement of GPU rendering

Yes, multithreaded processes, and background tasks, e.g., being able to save or export one document then switch to another, or continue working on a different task.

As new computers started to increase threads, rather than single thread performance, Illustrator stopped improving in performance (relatively speaking).

It's because it's not a multi-threaded app. That makes it way behind the curve.

There are some scenarios (such as the pattern making/editing tool) that absolutely halt to an unusable crawl if you do anything interesting with it. I believe it would be greatly helped by multithreading.

I'm probably not the first to mention this, but here's the annoying part: In GPU mode, performance is (usually) great! In CPU mode, it's more than horrible*. What's the problem then? GPU mode completely messes up colour display, with colour being one of the most important tools of a designer. Since this issue started, it has become increasingly cumbersome and error-prone to design visual identities in Illustrator.

Following Apple, Adobe seems to be less and less focused on quality control for the professional market.

*Macbook Pro i9 32GB 2018

The Kristina comment is spam. They are not from Adobe. You can tell this from the HP Support link in the comment. Not to mention the same comment was made by them on several other threads.

Please spend some of our subscription dollars on hiring better engineering resources. Can not imagine a giant technology company not having people who cannot do it. Even small software utilities make use of full processing power of my imac pro.

This subject is very interesting to me as I create banners for our company either for events like our fair, home shows all over California, and other places.

The largest I have done is a 15' x 6' (or 4.572m x 1.8288m, why? That is what they wanted. It is for roofing, solar, leafguard, and solatube. 300/cmyk. 70% is vector graphics and text, the 40% is large images of the products on houses. which were embedded the first time i sent it to the printer but the file was only 214MB. uploaded to google drive then they grabbed it.

the next time I did it, I unbedded them, sent the four 5mg images separately and sent the ai file which was no bigger than 32 mb.

Am I doing something wrong?

10:1 was just an example. Use the smallest that will produce acceptable results.

Here is an informative discussion.

https://graphicdesign.stackexchange.com/questions/487/what-resolution-should-a-large-format-artwork-for-print-be

Daniel, if you change your working dpi: Effects/Document Raster effects.../100 ppi Your life is going to be a whole better in wide format.

For interior wall signage/tradeshow I personally stick to 300, but that never gets to the physical sizes of exterior.