Because they're all written in C/C++, and it's impossible to write reliable software in C++ without a QA team that's 10x bigger than the development team.<p>But hey, at least it runs really fast sometimes!
I found that uninstalling flash stops my tabbed browsing sessions from crashing. With 2-6 flash ads per page, a typical session could have 20-50 tabs open, so that there is usually well over 100 flash adverts running. All it takes is a single advert to crash flash, then flash takes down the browser application.
I almost always have under 10-20+ tabs open.<p>I tried to use chrome but it always cries "Oh snap.." and all the tabs crap out (so much for individual). Firefox slows to a crawl, Safari and IE on windows both aren't even worth opening 1 tab in. So I stick with opera. It does the best overall job for lots of tabs. Although it takes quite a bit of memory..<p>With that said I really notice a lot of slowness on sites that use embedded fonts, more so then anything else. Next is flash, if I block flash from running my browser really speeds up. However Javascript has been replacing EVERYTHING. Even when it shouldn't it does, and is required by many sites, so I cannot turn it off, and some sites use a lot of resources for this mostly pointless js.
I definitely feel this too. I routinely have around 50 to 100 tabs open. This USED to be perfectly fine--no crashes, everything was snappy. Now firefox is crashing sometimes more than once per day on me.<p>I use noscript to prevent anything from running that is not strictly necessary, but still, regular crashes.
50 - 100 tabs open at one time!? Why would anyone need that many windows open? I'm not saying that these issues aren't prevalent--but I have to imagine that this is an edge case. Just thinking about ever having more than 5 or 6 tabs open at any given time just makes my head hurt...