Unfortunately, they miscalculated and thought that single threaded performance (specifically higher clock speeds) would continue to advance at the same pace as it has been before the release of Crysis, but what ended up happening instead is more focus on multithreading by releasing CPUs with more cores with smaller IPC improvements comparitively.

IPC improvements were obviously still a thing, but it took a while for hardware to be able to run Crysis maxed out at good framerates.