Windows? No. Tabs per instance in its single window? Yeah, quite a few, I'd say around 30-50 open file tabs at any given time.

I started the day by closing every instance, invalidating Rider's caches, and opening three solutions (medium to large size), one of which contains ~600 tests. Things felt smooth for a while, but it didn't take long before it became somewhat sluggish, freezing every 5 minutes or so for about 3–5 seconds. I might be biased, but whenever the freezes started, I'd close every tab in the instance I was working in. It felt like it helped — the freezes would still occur, but they seemed to take a bit longer to come back.



Iit really depends and feels somewhat random. Today it took about 1–2 hours before the freezing returned.

When I try to install from disk I get:
"Plugin 'NCrunch' (version '5.21.0.7') is not compatible with the current version of the IDE, because it requires build 261.21525 or newer but the current build is RD-253.31033.136"

I also have this since the "later" Rider Versions (not EAP). Sometimes Rider freezes when opening the Solution and the NCrunch Test Runner Tool Windows is active. Or when i switch to it.
(had the latest NCrunch Forum Version installed). Was good a while, but godd worse in the last weeks. Maybe an Rider Update was not good for NCrunch.

Will upgrade die EAP and give this Version a try.

Thanks for sharing this. It was very useful!

Here's my next try:
NCrunch_Rider_5.21.0.8.7z
NCrunch_Rider_5.21.0.8.zip

Ok, here is attempt #3

NCrunch_Rider_5.21.0.9.7z
NCrunch_Rider_5.21.0.9.zip

Can also say the freezes still happen. An NCrunch seems to be at least involved.
When I kill the nCrunch.Rider.EngineHost when the freeze is gone.

So this issue finally started happening for me with relative consistency, or at least, it started showing up when it felt like it.

I've been trying to analyse it for a few weeks now, and I'm presently working on a theory that it's being caused by NCrunch's CPU affinity handling. As with VS, NCrunch changes the processor affinity mask for the running Rider process (both the Intellij frontend and the ReSharper backend) so that it runs on different CPU cores to the NCrunch engine. The config wizard does this automatically and you have the ability to micromanage the distribution through the CPU core settings.

Under VS doing this is fairly harmless as long as the IDE has enough resources to do its work, though under Rider, when I have the IDE constrained, the freezes appear. If I set the CPU cores for Rider to be all available cores, the freezes so far haven't been happening.

So if you're experiencing this issue, make sure you have Rider set to use ALL cores on your system via NCrunch's config settings, then restart the IDE. I'm eager to hear if this solves the problem for you. If so, I'll modify the next build to make the CPU core settings ineffective for Rider sessions, since they then clearly aren't worth it.

After I cleared the Cores for the IDE. The effective value is now: 0,1,2,3,4,5,6,7,8,9,10,11,12,13
Less then before ;)

Try setting the cores for the IDE to EVERY core on your system (i.e 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27). It should be safe to overlap with NCrunch cores. The core splitting system was originally designed back when we were using quad-core machines. I doubt we'll see any difference on modern hardware.

If I'm right, you'll never freeze like this.

My theory is that something in the IDE is trying to allocate work onto specific cores, then is stalling when our core mask prevents it. The selected core might vary between sessions, which could explain why the problem seems so bad sometimes then at other times it never shows.

BTW 28 cores is pretty impressive for a laptop. That's some nice hardware.

Oh that does sound disappointing. Even on the specs, the TDP doesn't look too bad.

I'll admit that I haven't been terribly impressed with the later generations of Intel CPUs. The i9-13900ks I'm on right now tends to overheat at stock settings, even with around 10kg of custom cooling attached to it.

Please do let me know how you go with the CPU affinity settings change. Rider 2026.2 is quite close to RTM now and I'll need to make a decision on whether to disable affinity control for the IDE.