With a debug build I still can't reproduce any slowdown. The project is colossal and in my un-optimized build it took maybe 30 minutes to open. This suggests that anything that would be slow will be super-slow. However editing an action, or adding a new action, opens the dialog within around ~1 second.
I have a fully-patched Windows 10 with the Fall Creator's Update - version 1709, build 16299.192. The CPU is an i7-6700K 4 GHz, but as I mentioned before, running a debug build of C2 with no optimisations usually more than cancels out any performance overhead from this high-end hardware. The fact the project took so ridiculously long to open is a good example of that.
So I still can't reproduce any problem and I have no idea what might be happening. If the problem really is a recent Windows Update, then isn't the problem Microsoft's fault anyway? Is it fair to expect a small company to pick up the pieces of their mistake?
If it is taking 1 second to open, you are hitting the issue. That IS the issue (one of them at least, but this is the one I reported). If you go use a W7 machine, the dialogs are instant. Have you tried a non debug version of C2 with that project? Have you tried a W7 machine to compare? Have you tried another W10 machine? What exactly have you tried. From your responses, it seems you have not really done much debugging. We have collected a lot of data on this, have you even gone over it? To be honest, I am rather surprised at the lack of debugging and willing to work with us here on your software, when so many people have shown they have this issue.
On another note (this has been mentioned before, but I think you might have missed it given your response), this has nothing to due with how powerful (or lack of power) your machine has. I can load up my CPU to 100%, or 0% and I hit this issue. I hit this issue in a low-end and high-end VM. I hit this issue on a high-end and low-end computer. My computer can run multiple VM's and servers at once, but yet C2 fails to work well compared to a old 6 year old laptop.
It is not reasonable to ask Microsoft. They won't touch it. Not unless you can prove it is their issue and specifically with what (none of us users can do this, only you). WE (as in the users) don't know the real cause. Only you can find out the cause because you won't give us any debugging tools. You are the one who can look into C2 to determine the cause. All we did is a bunch of legwork. Ultimately, you are the key here to find out the issues root cause.
Let's be honest here for a minute. Your software is broken on numerous (in very high numbers) of W10 users. That is a whole platform for a major OS. That is C2's problem.
Only people with larger projects such as chadorireborn and I are affected the most (the projects don't even need to be that big). But, the issue still affects everyone. That is a huge concern for anyone on C2 who wants to grow their projects. That is a huge turn-off for anyone to even think about using C2. This again, is C2's problem.
We have done our best to show you the issue. Believe me, this issue is huge in terms of productivity. Even 1 second lost per dialog is days to weeks of effort over the months. Imagine for a second, every line of code you created for C3 had a 1-second delay to write (meaning 10 lines of code carried a 10 second delay in total before you can write another line). Now, picture having to restart your computer every half an hour because that 1 second turns into 4-5 seconds. How frustrating would that have been to write C3? Please, find out why it is taking 1 second, when W7 is instant. This is the root cause (again, you need to find out, we cannot find out for sure) of a much larger performance issue which leads to dialogs taking 5+ seconds, when W7 is instant.
I have done my best. It is completely in your hands — And to be completely honest, this thread should be used as a key factor for anyone who wants to use or buy Construct. It shows how willing you are to listen and to help users. As of right now, I have shown C2 is broken on a major platform, and you are unwilling to fix it. Please do your best to change that.