Jerky playback in DR 17 despite low resolution proxy files

After upgrading to DR 17 I am experiencing an extremely jerky playback in the cut and edit page. Right now the playback is next to useless for finding the timing of cuts. Could someone please advice?

I have tried the following:
* Bypassed color grades
* Enabled timeline proxy modes: 1/4 resolution
* Disabled all timelines but the current
* Created proxy files (see settings below)
* Generated optimized media
* Reduced the length and number of clips on my timeline

Proxy media settings:
* Proxy media resolution: 1/16
* Proxy media format: ProRes 422 Proxy

Laptop specs:
* MacBook Pro (Retina, 15-inch, Mid 2014)
* 2,2 GHz Intel Core i7
* 16 GB 1600 MHz DDR3
* Intel Iris Pro 1536 MB
* macOS Mojave, version 10.14.6

I know my computer doesn't meet the recommended specs to run Davinci Resolve but the playback has not been choppy before. To this point I have come a long way by just generating optimized media, be it in a resolution in which the content is hardly identifiable. =)

In Finder my files can playback smoothly. The resolution of a proxy file is merely 256 × 135 (!). How come DR has to struggle so hard to playback the files?

What can I try next?

PS. I am about to buy a new computer but I am waiting for the RTX 3070 graphic cards to be back in stock...

Update: problem solved

In addition to the other performance boosting actions I took, I lowered the timeline resolution to 1920x1080.

Funny how did step is not mentioned in tutorials online. Have to make sure to revert to 4K before exporting.

That method has been mentioned dozens of times here.