JDK 6u25 and 6u26 high memory usage

[ebogaard]

I've been running 3.4d for quite some time on Centos5.6 and JDK 6u23. Because 6u25 and 6u26 promise higher performance, I tried to upgrade to one of these versions.
Strangely, the memory usage skyrockets with both these JDK's. From ~700 MB to > 1GB. Ofcourse with the same configuration:

-server -Xss512k -Xms600m -Xmx600m -XX:MaxPermSize=512m -XX:NewSize=300m -XX:ReservedCodeCacheSize=64m -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:CMSInitiatingOccupancyFraction=80‍

I tried this on x86 and x64 version of Centos + matching JDK. If I return to 6u23, everything is normal again.
Anyone any suggestions why this happens and if something cane be done against it?

[ebogaard]

Did no one else notice this increase in memory usage?
As I said: I tried it on 32 en 64 bit Centos 5.6 and the increase in memory usage is significant. On another Alfresco instance on Windows Server 2008r2 x64 this increase doesn't show.