Early system modelling is an essential tool to accelerate software development, architectural analysis and hardware verification in complex many-core system-on-chips (SoCs). Transaction level modelling (TLM) offers a higher level of abstraction than register transfer level (RTL) and can be used for early system modelling. Maintaining simulation speed with the right accuracy is a major challenge and this paper proposes SystemC-based architectural modelling techniques that extend TLM to deliver faster simulation models for many-core system. The proposed approach considers a micro-scheduler for large modules (in the sense of SystemC modules) to locally manage all events in the module. Exploiting this micro-scheduler along with function object and coroutine concepts, the authors propose a lightweight thread process that significantly reduces the context switching overhead among the different processes. Additionally the micro-scheduler allows some processes to be run ahead of simulation time. The proposed techniques are applied to the model of a very large networks-on-chip (NoC) formed by thousands of cores stressing the simulation capabilities of the host computer and operating system. The experimental results demonstrate that the model can run successfully and exhibits up to 93% improvement in simulation speed compared to traditional SystemC-based modelling.