Emulator

We enabled more accurate CPU emulation for a feature... the fact it's slightly slower in some spots when using that feature isn't particularly a regression. We could disable it for this game or something but honestly I'm skeptical. Considering the old method ended up with off-by-one shenanigans, I don't want to go back to it.

Okay now that I'm up and less cranky, what kind of stutter is this? Is it like a "oh I'm running around fine- WHAT" where there's a hard stutter and then it returns to normal? Or is it a more general slowdown that lasts a couple of seconds? I wonder if the codecache is getting overflowed and it's just struggling or if it's really spamming this really obscure function.

If it were slightly slower it wouldn't be a problem, I mean I get 250% speed in this game and going to for example 200% wouldn't be a problem, but the problem here are the stuttering events (going from 250% to 50%) that plague the game ruining in this way the emulated gameplay.
Since I have a powerful PC and I don't think it is speed related, I suspect that this kind of bug would come out even with the strongest computer on earth...also are we sure this is the only game affected? I will investigate and report it (for now quite obviously Disney Epic Mickey 1 is affected as well)

Someone would need to say why it's happening before anything can be done.

It's a hard stutter that last sometimes 1-2 seconds, sometimes 2-3...

I see it when testing, I wonder if it's the codecache issue.

It's probably clearing the code cache or something, or it's firing off a shitload of instructions. This is rather interesting to say the least.

Just verified - it's clearing the code cache. Not my fault!

try this build - https://dl.dolphin-emu.org/prs/pr-8024-dolphin-latest-x64.7z

With that build the stuttering has moved from the title screen to the loading screen (now it doesn't stutter when you press A button to access loading screen, but it stutters when you click on a saved game to load)
As for in-game stuttering I need a bit more time to test if it's gone...

as expected during gameplay there's still some stuttering, maybe a bit less than before but due to the random appearance it's difficult to tell...

This is normal and would happen in old builds. I could make you another hacky build that delays it more or less indefinitely, but, it would use a tremendous amount of ram.

it doesn't happen in old builds: 5.0-8007 and previous builds are absolutely stutter free with Disney Epic Mickey 2 (at least on my system)

Forgot to mention in my System specifications that I have an SSD Hard Drive, if that somewhat matters...

I have epic mickey, and while it takes longer, it absolutely will stutter after a while.

I guess the old codepath is still being hit a bit in Disney's Epic Mickey, ballooning the jit cache hit still. I could get you a build with gigantic caches to confirm this if you want.

ok, let's try to confirm that...

P.S. Epic Mickey stuttered a bit with my 2nd PC (intel Core duo quad) but with the new PC I never had similar problems until 5.0-8009

I mean on that older PC it could just be general performance issues.

I'm going to make you a build I don't recommend you use outside of testing this as it will eat up a ton of RAM. Even if it works, it's obvious that we'll have to find a more permanent solution to reduce the JIT cache hit.

I've made two builds here. One build is a normal Dolphin build based on current master with the message enabled that tells you when the icache is cleared. The other is the same thing, except with all the various code caches made much bigger. I do not recommend you use it on a computer with limited ram.

https://drive.google.com/open?id=16LKihuPcNM-AgetzLoO-Qe-1pN7IEOOj

Copy them into a normal Dolphin install.

In order to satisfy GPL here are the two changes - https://github.com/JMC47/dolphin/commit/949b68307cd9fb8f480e6d130c613a45d9e64a4c

Ok here's what I found:

1. using Dolphin_Normal every time the game stutters comes out the message "Clearing code cache";

2. using Dolphin_Large_Cache the stuttering is gone and game plays like 5.0-8007;

3. meanwhile I tested Disney Epic Mickey 2 with latest master 5.0-10039 on my old PC (win10, AMD RX570, Xenia X5460) much less powerful and believe it or not, in the menus there's no stuttering at all (?!?)...could it be then a Nvidia only issue?

No, lol. It's a JitCache issue, just the timings of when the stutters hit will vary a bit depending on how the instructions are generated. Because an old PC uses some different codepaths, it may be avoiding some of the code bloat.

So, I'm going to have to disagree with your bisect once again. I've reproduced the icache clears almost as often in 5.0-8007. It's just delayed by a single menu screen. There's literally a log message that plays when the icache is flushed, if you enable logging and look, you'll see it before you get in-game.

The fact is that in 5.0-8007 there's no stuttering, while 5.0-8009 stutters a lot, so I presume that for some reasons 5.0-8009 is clearing the cache in a much slower way than 5.0-8007...

Now that I have an rtx 2060 super with 8gb I'm not experiencing this problem anymore, but in fact maybe it was 5.0-11318 that fixed this? In that case you can close this issue...