Adaptive refresh rate displays cause large frame-time spikes to appear when (only after) alt-tabbing between windows.

[ClarkieUK]

Bug Description

The above images were taken with G-Sync enabled in the Nvidia control panel, and adaptive refresh rate 'on' in monitor settings. Notice how the frequent frame-time spikes appear after alt-tabbing.

The above images were taken with G-Sync DISABLED in the Nvidia control panel, and adaptive refresh rate 'OFF' in monitor settings. No more repetitive frame-time spikes when changing contexts.

I'm not sure why this issue only appears after changing contexts, were the behaviour is otherwise fine on the initial launch state. I also noticed that the amplitude of those spikes were related to the setting 'CPU Render Ahead' where as the frequency was related to how saturated the graphics pipeline was, i.e if DH / Shaders were disabled, the spikes would still appear but at a much more spaced rate.

Also I was iterating through the in-game sync settings to see if it had any effect which it didn't so ignore the V-Sync enabled in the top left.

Should also note that in windowed mode the performance was significantly degraded too. Even without switching contexts.

Reproduction Steps

• Enable G-Sync / Freesync (?) in respective control panel + monitor settings.
• Launch game in Fullscreen.
• Inspect frame-time graph in-game after it's settled.
• Alt-tab, and re-inspect the graph, check if periodic spikes appear.

Log File

20260225-9.json.gz

Crash Report

crash-2026-02-25_22.03.38-client.txt

[douira]

To confirm whether this is a sodium issue or a vanilla issue, please check if you can reproduce this without shaders and without sodium.
Possibly related: #3335
I also vaguely remember an issue where a user was experiencing issues only after switching contexts, but can't find it atm.

[ClarkieUK]

In both vanilla and modded with sodium only, I get a baseline of 3ms with spikes reaching 8-9ms on a fixed period before AND after switching contexts. Although the graph is so noisy I can't really draw a reasonable conclusion. This is my first time debugging a Minecraft related issue. Could I log that frame-time information somewhere? I would love to graph it and fit for periodicity before and after switching contexts and applying filters etc...

After enabling shaders (even without distant horizons) with iris the very large periodic spikes then re-appear when switching contexts. I wasn't (and still am) not too sure where to focus the attention as I feel like the workload from the shaders probably amplifies the issue by quite a bit, regardless of it's origin.

***Edit:
More importantly just checked the following -> Restarted my PC , opened Minecraft first thing, was able to alt-tab just fine without the frame-time spikes occurring. Then opened discord, alt-tabbed, no frame-time spikes. BUT, then I alt-tabbed and interacted with discord, and the frame-time spikes appeared. I then closed discord and then the frame-times returned to normal. I have Hardware Acc disabled along with the In-game overlay... This is the strangest behaviour I've ever seen lmao, can also reproduce with 100% confidence. I also have no idea as to why it's isolated to when I only have adaptive refresh rates enabled.

[ClarkieUK]

• https://www.reddit.com/r/discordapp/comments/1pqh97l/discord_can_cause_stutters_in_your_game_no_matter/

possibly related, probably safe to close this in regard to any Minecraft components being responsible, a comment 2 days ago on the thread above mentioned registered games, and also that certain features broke when dealing with sync technology, hence maybe the adaptive result above ^ , good enough for me anyway.