Had to downgrade from CLion 2026.1.1 due to startup freeze

Same here. CLion has suddenly become completely unusable for me with 2026.1.1, on macOS 26.4.1 on a very beefy MacBook M4 Max with 128 GB RAM.

Build works fine, but when running tests, it gets stuck in the “Preparing…” step, with no indication what it's actually doing. After more than a minute, it switches to “Instantiating tests”, but nothing happens. In Activity Monitor, CLion ist mostly idle (single digit CPU utilization), and the generated unit test binary is at 100% CPU.

This turned out to not be a CLion issue. The problem disappeared after upgrading from Xcode 26.3 to 26.4 (CLang 17 to CLang 21).

Alex, what you're describing sounds a little different from what I am describing.

This has now happened on a second Ubuntu computer for me. My beefy home workstation now refuses to load my primary work project, with the same failure mode:

Launching the IDE gets it stuck in a “permanent” (20+ minutes, seriously) of “Analyzing project to enable smart features”. It hangs in this state, fails to load the CMake project(s), fails to initialize parts of the UI, and is generally totally unusable at the 2026.1.1 release. Downgrading that computer to 2025.3.4 resolved the issue, but I think I was also running just fine under 2026.1.0 (which I can't select as an installation target in the Snap store).

Yeah, it really sounds different. Based on your comment, I downgraded to 2025.X with the installer provided by JetBrains (and ignoring all the errors stemming from mismatched plugins) and hoped that would solve the issue. But when I built the project with just plain CMake, the generated CTest binaries exhibited that same behavior of just running at 100% CPU and not doing anything. The mistake I made was upgrading my OS to the latest macOS version and not immediately checking if my projects still compile.

Jacob McCollum, please check if the idea.log files from the CLion 2026.1 logs directory (~/.cache/JetBrains/CLion2026.1/log) contain the following message:

PerformanceWatcherImpl - Thread pool exhaustion: Dispatchers.IO is not responding for 5000 ms

If so, then you might have faced IJPL-243672. 

If there are no such messages in the logs, please send an archive of ~/.cache/JetBrains/CLion2026.1/log to clion-support at jetbrains.com along with the link to this thread. Thank you in advance! 

Note that logs may contain private user information (such as file paths and names).

I think the main issue here might be related to how structured data is being handled or displayed within the project. In similar cases, I’ve worked on modeling something like a sonic frozen menu as a dataset, where each item (like shakes or slushes) has attributes such as type, size, and customization options.

One thing that helped was separating the data layer from the UI logic. For example, defining a clean model (like a MenuItem class) and then mapping it using JSON made things easier to manage and debug.

Also, if you're working with large or nested data, IntelliJ sometimes struggles with indexing or recognition unless the structure is clearly defined. You might want to check how your schema or object hierarchy is organized.

Would be helpful if you could share a bit more detail about your setup or code structure.

Anna Falevskaya I opened an internal YouTrack issue where you have associated my problem with a known problem related to thread pool exhaustion and the Git plugin. This thread can be closed, I'll continue to follow progress there.

Chris, that's not the case here. This issue is related to a plugin.

2026.1.1 is absolute disaster. code navigation does not work. lags.

Hi I I Zaytsev!

Please create an issue in our tracker and provide the result of Help | Collect Logs and Diagnostic Data in it. Note that logs might contain private user information (like file paths and names).

I’m also experiencing same issues with I I Zaytsev and Jacob McCollum 

Nam Nguyen Dinh, there is the following performance regression in CLion 2026.1.1 - IJPL-243672. 

If the issue started happening for you only in CLion 2026.1.1 (CLion 2026.1 worked fine), and you have the following messages in the idea.log file (Help | Show Log in…)

PerformanceWatcherImpl - Thread pool exhaustion: Dispatchers.IO is not responding for 5000 ms

then you might be facing IJPL-243672. Please try disabling the Git plugin in File | Settings | Installed and restarting CLion.

If you observe something different or disabling the Git plugin doesn't help, please create an issue in our tracker and provide the result of Help | Collect Logs and Diagnostic Data in it, so that we can investigate the issue you're facing. Note that logs might contain private user information (like file paths and names).