OS: Windows 7 x64
Audacity: 2.1.0
After downloading Noise Gate I used it for the first time. After that everything in my project became unbearably slow. To listen to it fully took me almost 3 times the time that it is. To use the Equalizer now it takes an entire hour where previously it was only a couple of seconds. What’s wrong? Is it always like that after Noise Gate? Or did I download a bad file for it?
Okay, I think I’ve figured it out. It seems that when I used Noise Gate it created files on my deskpot for each track under the folder “HZD_data” (the project is called HZD). In total they took up 90gb and made my C disc almost full which made it slow so I decided to delete all of it but then found out that my project became empty 
It’s self-restoring now (miraculously). Is there any way I can change the pathway for the files so that it’s reallocated to D instead?
The easiest way is to save the project to the D drive. (“File menu > Save Project As…” then select a suitable location on the D: drive.)
There’s an informative article here about managing projects: https://manual.audacityteam.org/man/audacity_projects.html