I don’t think there is a computer available today that would handle arbitrary Dorico projects of extreme size without exhibiting some kind of delay when you make edits. Dorico does make use of multiple CPU cores, but because in the end each edit has at least one point where Dorico has to collate the results of processing individual staves and instruments processed in separate threads (and therefore often on separate CPU cores), there are always points at which the processing is single-threaded.
It is also the case that there are aspects of Dorico that are simply not fast enough. Dorico is a complex application and there are literally hundreds of individual processes that have to be completed for every edit. There is more work to be done on trying to improve the performance of these processes.
There are also things in the user interface itself that could be made faster, such as support for hardware acceleration in drawing, so that zooming, panning and scrolling are faster even on displays with very large resolutions.
In short, I would guess that even if you were to run the brand new top of the range M1 Ultra found in the $6,000 Mac Studio that was announced last week, Dorico would still occasionally keep you waiting when performing a large edit.
We want to improve the performance of the software but it is not a quick or easy job. Right now we are focused on bringing Play mode’s functionality back up to par with Dorico 3.5, and polishing some of the other new features added in Dorico 4. I hope that we will be able to devote some engineering time to addressing some of these performance issues in the coming months, but with our small development team, time spent working on performance issues means that it can’t be spent elsewhere, meaning fewer new features and expanded functionality in future versions. So everything is a trade-off, in development as in life.