This mirrors my experience. I had been using Ubuntu MATE for a few years without any issues, 30-40 days of uptime with no hiccups. Switched to Fedora to just try it out and it's really iffy. GNOME shell hogs memory and CPU for god knows what reason, I have a mid range Intel CPU + 32GB of RAM and it still lags heavily after the system has been up for more than 5-6 hours. I am stuck with this until my current gig is finished, will be moving back to MATE as soon as possible.