Unsuably slow

Instead of letting me work faster, each new version of Premiere slows me down. Previous version was bad, but it's worse now.
Sometimes it doesn't react. When I click on the buttons, or move the cursor the graphic feedback is there but the action is not performed. It's delayed a lot. The playback takes minutes to begin after I hit PLAY, and minutes to stop when I hit STOP, even when I switch to other apps, it keeps on playing in the background until I close the app.
If I wait long enough to see it work, it's fine for a while, but if I hide a track it becomes unresponsive again when I try to play. And the same when I show the track again.
I hide and show tracks all the time while editing, so this makes any simple edit ridiculously long.

I have a 1920x1080 timeline with two video tracks active (one 1920x1080 and one 3840x2160), about 80 minutes long, with total of 3 audio tracks. A very simple project. I'm using Quicktime prores 422 LT proxies at 1/2 resolution, but it really doesn't help.
I tried the usual fixes: 1/4 quality view, proxies, low quality previews, separate scratch disks, no audio hardware input, importing into new project, clearing caches... nothing helps. What's going on? Are they optimizing the app for Windows 11?

I'm using v 25.5.0 (build 13) on a Windows 10 PC with plenty of scratch drives:
Processor: Intel(R) Core(TM) i7-7820X CPU @ 3.60GHz
Installed RAM: 16.0 GB (15.7 GB usable)
Storage: 3.64 TB HDD WDC WD4005FZBX-00K5WB0, 1.82 TB SSD CT2000MX500SSD1, 119 GB SSD M4-CT128M4SSD2, 7.28 TB HDD WDC WD8001FZBX-00ASYA0, 466 GB NVMe Samsung SSD 960, 233 GB NVMe Samsung SSD 960
Graphics Card: NVIDIA GeForce GTX 1080 (8 GB)