Hello , I try to use 4K Youtube to MP3 but have some problems .

I am using version 25.0.2.0185 x64. When I installed the software, it worked perfectly. But when I shut down the computer and restarted it the next day, everything went wrong. The program was incredibly slow, took 8 hours to download 19 songs. Later it became even slower. I reinstalled the software, also tried on another computer, and this several times but the program became incredibly slow. I have a license that I pay monthly. I have written to the technical service but have not received a solution. Does anyone know what I should do?

Thank you , Marco