The hardware specifications required for optimal performance depend on various factors beyond the number of threads. For instance, the size of your contact lists, whether you are sending messages to segments or lists, the number of triggers in action, and the number of segments created, among others. If I were to assist you in running one hundred (100) threads, I would recommend a machine with over 50 cores and 128GB of RAM to ensure optimal speed. However, it is possible to achieve 100 threads on smaller machines with specifications such as 8GB RAM and 8 cores. Nevertheless, it is essential to note that utilizing threads without sufficient server resources would serve no purpose.