15.1 - no 'Performance Mode' = no smooth playback?

I had a workable setup with my Dell XPS 9560 + GTX1080ti in an eGPU. Using Render cache (which the 1080ti generates very quickly) I was able to get smooth playback in a 4k timeline. Just updated to 15.1 and can't get smooth playback at all no matter what configuration I try in terms of render cache or source media locations or adjustments to any of the timeline or playback options in the app configurations. If I disconnect the eGPU I can get smooth playback for a short time until the CPU and onboard GPU heat up and start throttling and the playback grinds to a halt.
I notice that 'Performance mode' is now missing from the playback options.....

I notice that 'Performance mode' is now missing from the playback options.....

it's now in User Preferences

I notice that 'Performance mode' is now missing from the playback options.....

it's now in User Preferences

Thanks. Doesn't seem to make any difference unfortunately (set to auto)

Tried some more options and changes to the setup but playback is a stuttering mess. Installed the first version of 15 but it can't open the timeline as it hangs at 98%.

The same here, on an iMac (2017, i7@4.2GHz, Radeon Pro 580, 32GB RAM, 2TB SSD). DaVinci Resolve Studio 15.0.1 playback was butter smooth in 4K timelines - with several grade nodes, stabilisation and some OFX filters on CinemaDNG 4.6K footage. Now it stutters so hard that it makes editing almost impossible.

I really like the new BRAW format, but Resolve 15.1 still needs some polishing, I guess.

Can't even render out the cache without it crashing now - unusable in it's current state and no way back!

The latest NVidia driver was limiting my system FPS to <24 fps - tested on Cinebench and other GPU test apps so rolled this back and it's back up to normal levels but Resolve is still not playing back smoothly. Any idea how I can roll back to 15.0 and still open a timeline saved in 15.1?

XML

Solved by disabling a 'glow' filter on the timeline node and smooth playback has returned.

I can "solve" the problem by disabling stabilisation on some clips. But it's not much of a solution, the same project had perfectly smooth playback on Resolve 15.0.1. It's just a workaround until an upgrade will solve this.

What was the conclusion here, same project with same actvited nodes/effects is slower in 15.1 compared to 15.0 or not?
Any reason to believe the behaviour is isolated to Mac?

1. Yes, exactly the same project is playing back poorly in 15.1, whereas it played back smoothly in 15.0;
2. Not sure if the problem is Mac related, and I don't have a PC with similar specs as my iMac for a fair comparison.

What was the conclusion here, same project with same actvited nodes/effects is slower in 15.1 compared to 15.0 or not? - yes
Any reason to believe the behaviour is isolated to Mac? - no it's on my PC

Thx Cosmin, John. Appologies for not noticing John was on non Mac, clear in the first post!
Anyway, this deserves more attention then I can see in the forum, possibly also a new heading since the Performance Mode was unrelated?
I'll carve out some time to do the test myself, benchmarking on 15.0 before upgrading to 15.1

Thx Cosmin, John. Appologies for not noticing John was on non Mac, clear in the first post!
Anyway, this deserves more attention then I can see in the forum, possibly also a new heading since the Performance Mode was unrelated?
I'll carve out some time to do the test myself, benchmarking on 15.0 before upgrading to 15.1

Yes I tried to change the title to remove the reference to Performance mode but was unable to. On the other hand in 15 there is Performance mode in the Playback pulldown and also in the user preferences so is this actually the same thing?