Managing software performance debugging based on a distributed VM system is provided. In response to determining a debugging state of a software system running on a VM, a timing of a system clock of the VM is controlled. A data packet sent to the VM from another VM is intercepted, and an added system time and reference time that indicate when the packet was sent by the other VM is extracted from the packet. Based on the system and reference times, as well as a reference time of when the packet is intercepted, a timing at which the packet is expected to be received by the VM is calculated. The packet is forwarded to the VM as a function of a comparison of the timing at which the packet is expected to be received and a system time of the VM when the packet is intercepted.