I’ve downloaded and installed Audacity 2.3.0. (zip file).
https://www.audacityteam.org/download/windows/
It works (built-in and Nyquist effects) very slowly. What’s to do now? But Audacity 2.2.2 works fine while I have to use it. Is it just me? Hardly. Please clarify and, if possible, correct it.
I see no speed differences between 2.2.2 and 2.3.0 - I’m running on both Windows 10 and macOS High Sierra and now on Mojave.
Is there anything in particular that you see as slower?
WC
For example, mutron, limiter. Very-very long.
Ok so I took a one-hour project and tested (on W10 64-bit SSD)
Using Limiter
a) on 2.2.2: 2 mins 38 secs
b) on 2.3.0 : 3 mins 38 secs
so a circa 50% increase
But the I re-ran the tests and while 2.3.0 stayed the same the 2.2.2 came in at a mere 20 seconds so 5x longer on 2.3.0 versus 2.2.2 
I would like to do some more tests but there are too many to test all of them - do you have a small set of other ones that also work slower in 2.3.0 compared with 2.3.0
I will probably be logging this as a bug when I have more data
WC
Appears to be a Windows issue as the same tests on Mac Mojave yield almost identical times of c. 30 seconds for 2.2.2 and 2.3.0
WC
On Linux, with SSD, I’m seeing around 20 seconds for that test.
It would be good to know which effects have this problem on Windows, and which don’t.
Unfortunately, that version, 2.3.0 has already been deleted and I will not restore it yet, since it is actually unusable on my computer due to slow work. But while it was still there, I’ve checked, and in my opinion, there are problems with all Nyquist plugins, in particular, High Pass filter (LFO). And the difference is not 50%, but much more, which is extremely disappointing.
If you would like to help resolve the problem, you could install is self-contained “portable” version of 2.3.0 for testing purposes, and continue using your old version for production work. If you’d like to do that, just say and I’ll show you how to make portable version (it’s easy).
Well, look, I import the usual 3-minute file, immediately apply Limiter - and see how long it lasts! 21 sec!
Similarly, High Pass Filter (LFO) - 20 sec! Before - 2-3. And so on. And import, change speed - is normal. Please correct!
Hi юра00
yes you are absolutely right - from some extensive testing I did today with 1 15 minute stereo project on my W10 laptop and my Mojave MacBook Pro (both fast SSD machines) it looks like something happened in 2.3.0 to slow down all the Nyquist Effects and Generators. It does not affect the Built-in, above the line Effects and generators and it does not affect Mac.
See attached spreadsheet for my test results.
I shall shortly be logging this on out bugtracker as a high priority bug.
Thanks you so much for your original report - very much appreciated, 
Peter
Speedtests 222 v 230.xls (21.5 KB)
Good news - we have found and fixed this bug so the fix will bee in our next release (which is planned to be a shortish maintenance release).
I tested the fix yesterday in the alpha test build and we have restored the timings to their previous levels (see attached spreadsheet)
Bug thread: https://bugzilla.audacityteam.org/show_bug.cgi?id=1991
I note that Limiter is still taking a little longer than previously - but nothing like as outrageously slow as now in 2.3.0.
Peter
Speedtests david’s fix 221 222 v 230.xls (22.5 KB)