FYI, have been running kernel 4.18.0-0.rc0.git10.1.fc28.x86_64 since a day, haven't noticed any breakages :-)
But 'swapper' process seems to be hyperactive compared to the fc28 4.17.6 kernel. Output from $perf top -sort comm,dso
28.20% swapper [kernel]
6.44% konsole libQt5Gui.so.5.10.1
5.85% plasmashell [kernel]
5.76% Xorg [kernel]
4.00% konsole [kernel]
3.87% kwin_x11 [kernel]
2.96% QXcbEventReader [kernel]
2.74% Xorg
libc-2.27.so 2.66% firefox libxul.so
2.50% swapper [unknown]
2.35% kworker/0:2-mm_ [kernel]
2.34% kworker/1:1-mm_ [kernel]
2.01% irq/51-SYNA2B29 [kernel]
1.72% Xorg Xorg
1.54% InputThread [kernel]
1.42% konsole libkonsoleprivate.so.17.12.2
1.32% plasmashell libQt5Core.so.5.10.1
1.06% konsole libharfbuzz.so.0.10705.0
1.03% firefox [kernel]
0.92% konsole libQt5XcbQpa.so.5.10.1
0.76% kworker/u8:4-ev [kernel]
0.75% kwin_x11 libQt5Core.so.5.10.1
0.72% konsole libQt5Core.so.5.10.1
0.72% perf libslang.so.2.3.2
0.69% kworker/0:3-eve [kernel]
0.60% perf [kernel]
0.58% kwin_x11 i965_dri.so
0.48% plasmashell libglib-2.0.so.0.5600.1
0.45% rcu_sched [kernel]
0.43% JS Helper libxul.so
0.39% konsole
libpthread-2.27.so 0.39% kwin_x11 libkwin.so.5.13.3
0.37% kwin_x11
libc-2.27.so