I've finally managed to make my Firefox usable again under amd64 Ubuntu by installing the proper version of 64bit Flash player directly from Adobe (current version is 10.)
I don't have stupid problems with stupid npviewer.bin anymore and my notebook finally doesn't lag.
Here's what you should do to install a native 64-bit version of Flash under Ubuntu:
- First of all, uninstall the original flash player:
sudo apt-get remove flashplugin-installer nsplugin-wrapper
- Download the 64-bit version of Flash player for Linux from Adobe 64-bit Flash download page
tar -xf libflashplayer-10.0.42.34.linux-x86_64.so.tar.gz
- Replace the old Flash player with new one:
cp libflashplayer.so /usr/lib/mozilla/plugins/
That's it. You now have a non-laggy Firefox.
If you are interested, I've also stumbled upon this ubuntuforums thread: http://ubuntuforums.org/showthread.php?t=1358591. The guys there, however, do too much in my opinion - it looks like rocket science and shooting sparrows using a cannon for me.
P.S. I have found the logo image for this post while googling for 'firefox icon'. Clearly it will become a new firefox logo very soon.