Lightroom Classic is slow causing me to use Bridge for my initial image review & edits

LR Classic has always been slow for me, I've mainly stuck with Bridge for image reviews and edits. However, I love Lightroom's catalog functionailty and would love to only use that going forward. That's what a majority of photogs do and life would be easier. But the speed issue is enough to prohibit me from doing that. I'm hoping this can be adjusted somehow.  Apologies for the length of this post, I wanted to inlcude as much info as possible.

To start, here is my system info:  https://d.pr/i/WNZNy1 

It is a 2014 iMac but appears to have enough processing power, memory and a new Samsung SSD to handle this. Would you agree this is suffucient? 

I am fully up to date with all software and have tried all the things recommended below:

- Reset LR prefernce files: https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/

- Tried each option under Performacne > Graphic Processor (auto / custom / turn it off)

- Read this article from Adobe: https://helpx.adobe.com/lightroom-classic/kb/optimize-performance-lightroom.html

- Tried moving my LR catalog to my internal startup SSD.

- Reformatted my SSD and started a new LR catalog, the current LR catalog only has about 250 images in it.

Slowness when previewing and reviewing images:

One of the first things I like to check after importing a set of images is how well the focus was hit. This can only be done properly if you view the image at 100%, and doing that takes LR 3-4 seconds to display the view. A low-res preview loads pretty quickly when I select a new image from the filmstrip, but trying to view it at 100% takes 3-4 seconds.  This makes it very long to cull a set of images from a shoot.  

See this video as an example: https://d.pr/v/P5agby ... you'll see me click on different images and LR shows a low res preview, then 4 seconds later the crisp image loads. In all fairness, when using the loupe in Bridge to view 100%, it doesnt happen right away, but it only takes 1-2 seconds.  LR is 2x as long.

As a note, I am on the Develop tab when doing this because the Library tab only shows a "embedded preview" which doesn't really show the quality of focus I'm looking for. It's decent, but not as good as viewing 100% on the Develop tab.

Slowness when editing images:

Then once I start editing, it seems to slow down even more. Making the edits is not necessarily slow, for example changing the white balance happens quickly. The slowdown happens when I try to view that image later on. An image that has no edits on it will load faster than an image with edits. Some may say "duh", it has more data to read! But I can't imagine that is normal, it wastes a massive amount of time just for one folder of images, let alone thousands.

Secondly, if I add an adjustment layer with the brush and selctively edit some part of the image, it majorly slows down when displaying the preview after I'm done. Again here, applying the brush and edits is not necessarily slow, although if I have several adjustment layers it will slow down when performing the edits. The main issue is getting the crisp preview of the image to load later on when I go back to the image to review it. The area that I've used the brush on will be low-res pixelated looking, and will take a good 6-7 seconds to show the crisp high res edits on the image. 

See this video for an example: https://d.pr/v/AxmZ0R

Look at the clouds and sky when I first click on the new image. After 6-7 seconds it will get nice and crisp. I then click on another image that has adjustment brush edits, and you can see it happen again.

Does everyone feel that is normal behaviour?