Scalability cont.

Thanks for all the comments on my last post! Due to popular demand I was also running the tests on Opera. During the first run Opera crashed after opening 140 tabs. The crash ID was “crash20110803153559?, whatever that means.
The following runs were more successful but I noticed a slowdown during rendering after about 120 tabs.
The timing results for Opera 11.50 are:

real    6m55.074s
user   5m23.217s
sys     1m13.607s

The results are similar to Firefox. Opera uses a single process with 290 threads and 2.5GB of RAM. For comparison: Firefox uses 27 threads and 2.02GB of RAM.

I was also running the V8 benchmarks on Opera with 150 other tabs:
Score: 2719
Richards: 2665
DeltaBlue: 2027
Crypto: 3213
RayTrace: 4440
EarleyBoyer: 3135
RegExp: 1008
Splay: 4515

Opera with a single tab:
Score: 4028
Richards: 3901
DeltaBlue: 2999
Crypto: 4625
RayTrace: 5596
EarleyBoyer: 4744
RegExp: 1543
Splay: 7766

The JavaScript performance is pretty good. Firefox got 3954 for 150 open tabs and 5125 with a single tab. The browser is still responsive but closing 150 tabs at once takes about 30 seconds. I can’t provide any insights to the Opera event loop. Maybe some developers can help me here?