As promised I will keep you up to date about the problem in my previous post about the issues with ASM on Solaris when a large amount of files exists (or have existed). I can confirm that there is a fix now that completely solves the problem.
The solution consists of patch 6270137, which prevents the blocking effect of asm when scanning through the files. Support recommends installing as well patch 6264570, but I can’t confirm that this one is really necessary (I don’t think so).
Anyway, I must congratulate Oracle Support for their strong effert and quick solution of the problem (the patch is already out since 18 Mar, this blog article about it comes much later).
Oracle at work 
Hi,
From what I can see in the bug, it’s a duplicate of another one, and it seems to be related to the number of disks that can be used by ASM not the number of files in ASM.
There may be a relation between these, but it’s not evident from the bug.
rgds
There are indeed issues with large number of disks as well, but in our environment, there were only 2 asm disks. The problem was high priority at Oracle dev, so they looked into all existing issues and bugs. However only after creating and releasing the mentioned patch, the problem turned out to be solved.