Utorrent is still just a 32 bit app, and will never be 64 bit (and there is no excuse for that). Because of that, it runs out of memory when you have a lot of torrents.
I was re-downloading a massive number of torrents because the drive where the video files were stored crashed and died. This was going well, but then I noticed that it stopped, and no new torrents were being downloaded. I then loaded the exact same torrents into Qbittorent and they downloaded VERY quickly.
I would also mention that starting in version 5.0, they made Qbittorrent transfer bigger chunks of data, so it goes even faster.
In your download client, look at who is using what clients. You will see that the vast majority are using Qbittorrent, and almost nobody is using Utorrent.
I noticed something else. At the same time Utorrent stopped downloading anything, it's stupid video advertisements started running again. So... goodbye Utorrent! There is a very easy and fast utility that I uploaded a couple of years ago to migrate all the torrents from Utorrent into Qbittorrent. I will be doing that next week after hurricane Milton is done destroying Florida.