i have some additional infos:
i did d-load :
garage band… studio one and reaper (demo versions…) and in ALL apps circle2 beta3 takes 5seconds for VST version, and 2,5 seconds for AU version till GUI appears… so i am shure, that circle2 is the problem … not the DAW. if its not circle, what else could it be? as i told, ALL other plugs opens in less than a second… i really hope you can find “the bug” cheers manuel
@stacker yes I agree that it is an issue with Circle and one I can fix for sure. The thing is that we are not seeing it here. My feeling is that it is something to do with the interface paint timers. I really want to figure it out, I think that is something related to the painting and your graphics card in the mac pro. For a solution it’s going to be tricky, I could try and get my hands on a similar system but it might not display the same problem and I feel it won’t. Leave it with me as I might have a flash of inspiration in the next day or so 
Hi @Gavin_FAW as said in another post I experienced the same issue on StudioOne and Windwos10
Yesterday one the same PC I had the same issue using Reaper. Circle takes more or less 8 seconds to appear as said other synths (i.e. Sylenth) takes no longer than 1/2 seconds.
If I can do something to help you to solve (i.e. you can connect to my PC) I’m available of course.
Cheers
hy gavin. what exactly do you mean by
cuber LE 9.5 ?
there is only a cubase 9.5 elements / 9.5 artist / and 9.5 pro
its maybe no so important… but anyway… greets manuel…
Cubase Elements Manuel 9.5 Manuel
hy gavin… thx fore the 9.5 info
btw. i installed now the “final” version… and… it “only” takes 3 seconds till vst-gui appears… it could be better… but thx anyway for this work 
i still hope that in the future it opens like it does in your DAW 
greetings from swiss… manuel
@stacker, I have further ideas on how to get the interface to open faster. I’m keeping working on it, we’re not going to just release 2.1 and then leave Circle development.
Next 2.1.1 will add NKS support hopefully and alongside that, we’re going to try to improve the interface opening times. Wish I had a similar system to yours there, definitely something to do with your multicore mac pro and the way we are handling threading.
hy gavin… i inst. circle 2.1.1 rc5 … gui opening time now 6seconds !!! in all vst hosts 
then i installed another older version (2.1.0 beta4) … still at 6 seconds… au version takes still 3 seconds. i still have no idea why circle (vst) dont like my mac… greets manuel…
hy gavin…
i installed all versions… current Circle-2.1.2.RC2-setup… still 6 seconds till gui appears…
greets manuel…
Hey @Stacker, Sorry for the slight delay in replying, this topic slipped down the forum due to the beta releases. To update you, I’m still trying to find out what is causing this. We have an open bug in our dev system for it so it is not going anywhere.
hy gavin… dont mind, but nothing changed till now… currently installed version 2.1.3 rc1 opening time under AU = 3.00 sec… VST = 6.00 sec
greets manuel
btw. i am just intressed in VST version…
@Stacker, yes it a hard one their is nothing different between AU and the VST, other than the host. I feel if I can recreate it then we will have a fix for sure.
On my side, I get a very snappy open as per the gif, this is the VST in 32-Bit Ableton Live. The key will be recreating the problem.
@Gavin_FAW not sure if this can help but if you need you can connect to my computer via TeamViewer or else to check, I have the same opening time in StudioOne and Reaper more or less 6/8 seconds. I’m on Windows.
@Residente, I’ll need to have a debugger attached so I can actually see where the issue is in the code. Thanks for the offer of going over and above to help though
@Gavin_FAW no problem lad, sorry for the “noob offer” 
hy gavin. now, with 2.1.3 rc5 , the opening time in my cubase just 1.5 to 2.0 seconds !!! thank you very much !!!
i guess, it was the overhoul of the font (?) but however… from now on, i am having fun to play with this synth again
maybe you can tweak it bit more
best greets manuel…
I can confirm that with 2.1.3-RC4 opening time is reduced in Studio One as well. Now it takes more or less 4/5 seconds, well done guys!
I’m still having the issue with Avast antivrus.
cool so far… but check it out again with rc5 version!!! they changed the font… im shure there was a big problem… greets manuel
That’s great news guys! We know what the problem is now. I won’t get into it too far, but it seems that the font smoothing which we turned off was causing a big overhead on some graphics cards! So happy we finally got to the bottom of it.