The worst of Intel's processor core asymmetry was with Meteor Lake and Arrow Lake, where the two LP-E cores on the IO die had no L3 cache and really bad DRAM latency despite being directly adjacent to the DRAM controller, resulting in those two cores combined offering about as much performance as one of the E-cores on the CPU chiplet. And they used the same IO die across both generations, while updating the microarchitecture of the CPU chiplet, so things diverged even more. And because the performance of the LP-E cores was so bad, Windows wouldn't schedule any threads on them unless it was trying to operate exclusively on those LP-E cores with the CPU chiplet powered down entirely—but those two LP-E cores were still reported to software in the total thread count, so heavy multithreaded applications would launch two more threads than could actually be scheduled at once.
With Panther Lake, Intel still has three tiers of CPU cores, but the performance gap between E cores and LP-E cores is down to only about 10%.