The only thing I want from Firefox is to stop freezing completely when a single tab goes crazy. It just makes the whole experience feel clunky compared to Chrome.
Usually it happens with Gmail so maybe there is a conspiracy there to drive adoption for Chrome :p
Multi-process Firefox (aka Electrolysis or just e10s) is till under development. If you want to test it, I recommend using Firefox Nightly (34) because it has recent e10s bug fixes and its File menu has a "Open e10s Window". You can test e10s and non-e10s windows without flipping an about:config pref or restarting Firefox. You can flip the optional pref browser.tabs.remote.autostart to true to enable e10s by default, which also enables extra "shims" for add-on compatibility so more add-ons will work than with "New e10s Window".
Chrome uses a separate render process for each tab[1], so when one crashes it doesn't KO the whole browser. However this also means Chrome has a larger memory footprint, since each tab is taking up the resources of a little browser. Firefox doesn't do this, and so it keeps a smaller memory footprint than Chrome (oh how times change) but the downside is--as you mentioned--the whole browser freezes if one tab fails.
Try changing the values of dom.max_script_run_time and dom.max_chrome_script_run_time in about:config to lower values so that unresponsive scripts can be killed faster.
tbh this happens to me more often in chrome than firefox these days..
i do get slowdowns in firefox when some tabs are loading tho. but the complete freeze in chrome is when the ui or something goes wrong, its rarely a single tab (which doesnt really happen in firefox)
Usually it happens with Gmail so maybe there is a conspiracy there to drive adoption for Chrome :p