I am doing server tuning, building up fast server systems for a very long time now. Yesterday i installed 1.2.1, expecting to see a far more matured Pharo Smalltalk, stable, pretty nice new features. I opened up the Memory Grapher, hmmm.... works fine, watching memory pumping. A bit strange, seeing a Pharo consuming and freeing megabytes of memory space without any load. But ok! Then i opened up TestSuites, marked some tests, let them run. Ups! Desktop hanging. I expected to have with Pharo a well done, stable multitasking environment, but Pharo hangs everywhere, is leaking lots of memory, is keeping up connections, wasting resources unneccessarily, having problems with internal race conditions on semaphores, mutexes, feels same like "Big Kernel Lock", but even without MultiProcessing. The Pharo Team IMHO is very much missing important knowledge about modern Operating System Design, what Pharo Smalltalk OS is in fact, without being able to fulfill the minimum standards i expect from a usable Smalltalk OS. As system operator or enterprise i cannot offer such a system, that has to be restarted twenty times a day, due to hangs, memory leaks, sucking connection handles, ..., whatever! tnx for your understanding! regards, Guido Stepken