Extensions/Addons are also running Javascript, so they can definitely be a factor in how responsive the browser is. Chrome is slightly better at utilizing ever

Extensions/Addons are also running Javascript, so they can definitely be a factor in how responsive the browser is. Chrome is slightly better at utilizing every computing resource available, but that also means that it is more resource-intensive. Now, every once in a while, I do experience Firefox being unresponsive. Restarting the browser always fixes that, even with the same browsing session. I haven't experienced Firefox locking up the entire system, except with really low resource computers (like Netbooks, or < 4GB of Ram).