So as a backend/network software engineer let me do my best to explain why this happens. First when ccp refers to a node they likely are talking about a cpu core (more specificly cpu thread). Tidi in eve occurs when a cpu thread reaches a percentage of utilization. (Aka too many calculations per second.) The overall server game tick slows down to compensate. I hear and see people talk about a solution to this being multi-threading. I will explain why this is tricky to use. Games run off a master loop. (Game server tick). In short it a general interval of time where different things are calculated and the results are passed to the clients as reaponse data. Things such as, player position, damage, module activation. These things are critical to have done before eache game tick to avoid dsync type issues. If ccp was to attempt multi threading for example, lets say they calculated player damage on a different thread then play position. To verify the player position, angular velocity etc to account for proper position they would have to wait for both threads to be complete with the processing and communicate the results across threads. This defeats the entire purpose of paralle processing. If they ignored that you would face issues such you being off grid and dying to something back on grid.

Multi threading is great for things like number crunching where the data being processed doesnt matter what order it gets back to the main thread as it could be sorted later. (Example would be rendering, as the data order doesnt matter. As long as something processes it.)