Bloat may be part of the problem, but I don't believe it to be the whole picture.

As Apple started moving to SSD's, I believe they stopped caring about minimizing disk seeking when considering changes to their virtual memory implementation. I had a Macbook Pro with 16GB of RAM and a spinning-rust hard drive, and was constantly getting beachballs when switching between applications (I had FREE RAM and was getting beachballs!!!).

(Apple's ~2012 virtual memory behavior was a strange beast -- it appears it would page an application's memory out to disk so that it could hang on to some disk cache. This was different than what I had become used to in Linux, which always prioritizes application memory needs above disk cache).

Disabling the pagefile solved the beachballs, but with the downside that when I did run out of RAM, the machine basically ground to a halt. I later upgraded that machine to use an SSD, re-enabled the pagefile, and was back to smooth running.

Is bloat the problem? Possibly. More likely it was shifting priorities (minimizing pagefile access probably just wasn't a priority anymore).

My experience mirrors yours on this front. I have several macs, one of which is an older mac mini with a traditional hard drive, which has become less usable as OS updates come in. However, the moment you replace the traditional drive with an SSD, the OS becomes responsive again.

Thanks, exactly the same thing happen to me and I thought the performance characteristic is different.

But if that is true ( Which align with my own experience ) this would really annoy me. SSD or not, it should ALWAYS fill up the memory first.