Most stuff just works. The X1 is a wonderful machine, although a bit short on RAM. It can absolutely do 3d and the i7 is reasonably fast.

make.conf (note that I use stable, an xcb issue recently broke houdini for me):

CFLAGS="-march=core-avx2 -O2 -pipe"
CXXFLAGS="${CFLAGS}"
USE="mtp modemmanager bluetooth samba -games mmx sse sse2 sse3 dbus -kde -qt4 gtk gnome systemd -consolekit -cdr"
PORTDIR="/usr/portage"
DISTDIR="${PORTDIR}/distfiles"
PKGDIR="${PORTDIR}/packages"
MAKEOPTS="-j9 -l8"
VIDEO_CARDS="intel i965"
# some like it hot
EMERGE_DEFAULT_OPTS="-j9 --load-average 8"
ACCEPT_KEYWORDS="amd64"
ACCEPT_LICENSE="*"

Man, they screwed up the trackpad. This is how I got it usable:

/etc/X11/xorg.conf.d/99-synaptics.conf

Section "InputClass"
        Identifier "Default clickpad buttons"
        MatchDriver "synaptics"
    
    Option "SoftButtonAreas" "60% 0 0 2400 40% 60% 0 2400"
    Option "AreaTopEdge" "2400"

    Option "TapButton1" "1"
    Option "TapButton3" "2"
    Option "TapButton2" "3"

    # Calm the pad down while clicking
    Option "VertHysteresis" "50"
    Option "HorizHysteresis" "50"

    # Drag lock
    Option "LockedDrags" "1"

    # Tap to click
    Option "FingerLow" "50"
    Option "FingerHigh" "55"
    
    # Prevent accidental clicks
    Option "PalmDetect" "1"
    Option "PalmMinWidth" "5"
    Option "PalmMinZ" "40"
    
    # Natural scrolling
    Option "VertTwoFingerScroll" "1"
    Option "VertScrollDelta" "100"
    Option "HorizTwoFingerScroll" "1"
    Option "HorizScrollDelta" "100"
    
    Option "MinSpeed" "1"
    Option "MaxSpeed" "1"
    
    Option "AccelerationProfile" "2"
    Option "ConstantDeceleration" "4"
EndSection