Also the attacker included in the 5.6.0 release the support for the long-awaited multi-threading decompression (and - broken - sandbox) making it very attractiv

Also the attacker included in the 5.6.0 release the support for the long-awaited multi-threading decompression (and - broken - sandbox) making it very attractive to upgrade to... It was probably a tactic to give a reason to upgrade. It's not always a fault for those who did or tried to do.