Cache don't mean swat. The Athlon x2 had much less cache then the P4s of the day, and they had no problems keeping up with the P4s. The higher end ones could even handle the P4 EE's, which had 2MBs of L3 cache. Like clock speed, cache is only one aspect of what makes a CPU "fast". You can't compare cache directly while ignoring other things. For example, the i7 might have less cache, but it has an IMC so it doesn't really need a lot of cache.