Originally posted by: VirtualLarry
I've been a long-time Netscape (since 1.0 16-bit for Windows 3.1) user, and then switched to Mozilla at around 0.9, and then to Firefox at around 0.6 (maybe 0.7). I've used Opera for a few weeks at various points in the past, usually when I was frustrated with the bloat of older Mozilla versions. I recently decided to get Opera 8 beta a spin, over Dec/Jan holiday vacation, since my FF 1.0 was acting up. (Crashing in JS3250.DLL - lated obtained an updated file that seemed to fix the problem.)
Anyways, unlike my experiences with earlier Opera 7.20 in comparison to Moz 1.2-1.4-ish, Opera 8 beta was decidedly a lot more bloated and sluggish than my FF 1.0RC2 is. It wasn't just my opinion, I had Task Manager open to graph the CPU usage, Opera 8 eats CPU like there's no tomorrow. It also had trouble decoding images occasionally. Overall, I didn't like it at all, it was worse than 7.x. The page-scrolling is buttery-smooth, compared to FF, but at the cost of major CPU time, and actual page-loading time in Opera was far worse than either FF 1.0 or what I remember of IE5. (This is on a 1.5M DSL connection - one would think that nearly any page would load "snappy", but that wasn't the case with Opera.) Perhaps this was all because it was still "beta", but I've used plenty of Mozilla/Firefox versions labeled "beta", and they were all more-or-less similar to the released versions.
So, in the end, Opera out-does Mozilla, in being even MORE bloated, slower, buggier... oh yeah, Opera cloned Moz's sidebar too.

All while FF 1.0 became faster, lighter-weight, and more "spry" than Opera 7.
Edit: Forgot to mention, Opera 8 beta had a lot of annoying rendering errors on some sites, things that FF didn't even have problems with. I tested by changing the user-agent strings to Moz and IE6 as well, in case the server was sending bad markup intentionally, but no change. If there's one thing that a browser should do right, it's render the page correctly, and Opera 8 was pretty bad in that regards. Perhaps they were doing a complete re-write on the engine or something? I dunno. It also causes some wierd machine crashes too, due to the strange way it uses modal pop-up windows for the URL location bar. (Even after attempting to minimze Opera, the URL bar was Z-order topmost,
on top of my other active applications!. Total PITA UI brokenness.)