Hi,
Does anyone else have this issue ?
IR is smooth with any other tab than Post, but with the latter, it’s a lag fest, unusable. It isn’t related to the scene, it’s happening even with a simple cube. It happens only with the VFB 2, not the Legacy one btw.
C4D 2025.3.3
Corona 14
Windows 11 25h2
Some people are experiencing some lag issues (including myself) - there will be a build out soon that should remedy this, do please test once that is out so we can confirm it’s fixed.
Seems fine on
W10 LTSC (1809); Cinema version • 2024.4.1; Corona Version • 14; Build timestamp • Nov 10 2025 20:47:19
note to devs: it’s the last C4D version that works w/ this OS version
BTW if this is the same lag issue, it does seem CPU dependent. Let us know which CPUs you are using. Mine is a 9950X.
amd tr 1950wx
AMD 7980X
So I just tried 14 update 1 on my 2024 install before upgrading on my main install and it still happens. You guys can try another shot at it, this thing lags like hell, it’s unusable.
What’s the issue with these lags on C4D ? Can a dev explain what’s happening ? Corona is laggy and sluggish in IR since day 1 on Cinema 4D, I’ve already done numerous comparison with the Max version where it’s buttery smooth and fast, and NOTHING has improved in 14 versions. The framerate is lower and it makes the C4D UI lag and stutter. Others render engines don’t have this issue on C4D, even V-Ray CPU is as responsive and as fast as elsewhere.
I love Corona - the look, the features - but these never ending bugs that keep happening or worst, reappear in newer versions, these regressions (hello motion blur and instances 
) drive me nuts.
I’ve been experiencing the same issue, I actually found a very simple workaround.
The IR lag in Cinema 4D seems to be strongly related to how the IR window is handled by the UI.
If the IR window is floating, performance becomes extremely sluggish: low framerate, UI stuttering, and general lag.
The solution:
Just dock the Corona IR window directly into the C4D interface (for example as a tab next to the viewport or in a panel). Once docked, the lag completely disappears on my end. The IR becomes smooth and responsive, and the C4D UI stops stuttering.
Hopefully this helps others, and maybe it can give the devs a clue that the issue is related to floating window / UI integration rather than raw rendering performance.
I can confirm this as well: when the window is docked, the viewport is much faster.
However, docking the window cannot be the real solution.
I think this is something the Corona team could fix quite easily, right?
Please fix it — workflow and performance are extremely important nowadays. @Corona Team
I just tried this and indeed IR+viewport navigation is more laggy in C4D than in Max, BUT when I switched the Windows power plan from “best power efficiency” to “best performance”, it became as smooth as butter. I am using a laptop with an i7-13800H CPU so it’s a pretty special case, but power plans can also make a difference on desktop AMD systems. There used to be special AMD power plans installed with Ryzen Master, so maybe you could check that just in case.
I understand that this is not really a solution, but hopefully could be a way to mitigate the issue.
I have also reported this to our devs as (Report ID=CC4D-1244).
@everyone with this problem - could you please check if the performance is the same for you in Corona 14 Update 1 and Corona 14 non-update? You can get it here: Download | My Chaos
The point is to check whether the slowdown is caused by a change we introduced in Update 1.
Thank you in advance!
Same in both
yes same
Continuing in support ticket #506923 (Tuami)
If anyone else is experiencing this specific issue - please send us a ticket at https://support.chaos.com/hc/en-us/requests/new