One of the tool authors here. The answer is "it depends". We absolutely designed sysdig and csysdig to work on production systems. They both work by capturing system events, so their cpu usage depends on the number of system calls in the system. On machines with average workloads, I would expect csysdig's CPU usage to be comparable or slighly lower than htop. On machines that do a lot I/O, the CPU will probably be higher. Memeory usage is typically some tens of megabytes.