Well, use task manager for basic performance monitoring
Here are some other things:
Install chromium which is open source chrome: sudo apt-get install chromium-browser
Flash for the last four sites in the world that use it sudo apt-get install pepperflashplugin-nonfree
VLC seems way better than the native player sudo apt-get install vlc
with all the codecs you will ever need sudo apt-get install xubuntu-restricted-extras libavcodec-extra