lumetri color optimization

That's a six year old CPU, with only 8 cores ... by "modern" standards, both old and a bit to the low side for cores. And I think perhaps neither that CPU nor the GPU has much capability for long-GOP "hardware" encoding. Affecting H.264/5 playback and exports.

Each major build version of Premiere, like all other major apps, is updated in coding and is built to utilize the newer hardware's more capable options. As the older kit doesn't have the new stuff, it's not as efficient in the app as much as it used to be.

So it works yea, but is nearing the time of replacement.  It will function better with prior versions, like the 24.x series. To use with 25.x forward, you will probably need to work smarter at things like proxies, transcodes and such.

Just a fact of computer Life. @RjL190365 would have the exact data on this sort of issue.

Hello, @Kevin-Monahan,

Thank you and sorry for the lack of information. It's true that this subject needs more information, I was a bit nervous about the delays I had to justify to my clients.

My processor is an AMD Ryzen 7 3800X with a RTX 2060 Super and 32Gb RAM. My project contains ProRes and H264. I'm working on everything from a 6TB Seagate external hard drive with a reasonable read speed. In this project I'm using Lumetri Color in every take and in an adjustment layer on top of all the scenes. This adjustment layer also has FilmConvert. I'm also using the native sound effects.

The point is, I've always had this workflow and it's never performed so badly since the last update. My renders, in that same scenario were fast and no process lasted 20 to 30 minutes as it is happening now.

It's also important to say that I've already updated the video drivers to the latest ones.
I hope I've given you the information you need.

That is sadly a near useless post. Performance is always dependent on 1) hardware involved 20 media involved and 3) any other user choices, effects, or plugins.

You haven't given enough data to even speculate why your performance has tanked so hard. For example, mine is actually a bit faster with the 25.x series of builds. On a 24 core 3960X Ryzen, 128GB/RAM, 2080 Ti system. All media on internal SSDs, and only 'native' audio effects applied along with Lumetri. Media is UHD BRAW, some mov mostly ProRes, a few clips of mp4 H.264 stuff.