If you’re in the same trouble as I was with black screen during boot(plymouth has the theme installed and even displays it during shutdown) then there is a small thing that has to be edited in order to get rid of this annoyance. Go to /etc/grub.d/10_linux and remove the **handoff=7 **parameter. Inspired by this and also this(pretty nice tool for configuring plymouth for dummies).
Had a real problem with my wifi after moving to Ubuntu from win -> my download speed was dead slow with ~2Mb/s. Tried various things including this this and finally this. The last one did the trick. It was Avahi which spoiled everything. The thing that led me to Avahi was this irritating message popping out each time I connected: Having this changed _AVAHI_DAEMON_DETECT_LOCAL=1 to AVAHI_DAEMON_DETECT_LOCAL=0 in /etc/default/avahi-daemon_ Got me up to 22Mb/s after reboot....