If you have a laptop with an Intel graphic card and architecture above Sandy Bridge (circa 2011), you can accelerate xorg significantly with this little hack. Create the file /usr/local/etc/X11/xorg.conf.d/intel.conf:

Section "Device"
  Identifier "Intel Graphics"
  Driver     "Intel"
  Option     "AccelMethod" "sna"
EndSection

See the manpage intel.4. It seems that the version of xf86-video-intel on FreeBSD falls back to the UXA acceleration method but forcing SNA provided good results on my ThinkPad X250.