I've been using the desktop app for sometime, and recently upgraded to the most recent version, but one thing that's been a consistent issue is performance.
Between the 'GoToAssist Agent Desktop Console' and 'QTWebEngineProcess' processes, before I know it my fans are spinning up and it feels like I'm moving my mouse cursor through Jell-o.
I'm on a MacBook Pro 2018 quad-core 2.7 i7 with 16GB of RAM running Catalina 10.15.7. In terms of other things going on concurrently, I am outputting to an external screen via USB-C, and have a few Chrome tabs open (let's say 5). Things get particularly bad if I need to hop on a Zoom at the same time, when my whole computer becomes pretty much unusable. In this time of COVID I can't avoid using Zoom at the same time, so as to avoid any responses that say to not run both programs at the same time.
It's also worth noting that if I use the Chrome version of the console, I don't have this issue at all. It's something with the app itself.