Performance Issues for MacBook Pro with M5 Max: Some Units Show Severe Drops in Multi-Core

Some recent models of MacBook Pro with M5 Max are showing anomalous performance behaviors, raising concerns among users and analysts. In particular, several tests highlight a significant inconsistency in multi-core performance, with variations reaching up to 41.5% between one benchmark and another.
The issue has been brought to public attention by YouTuber Zip Tie Tech, who conducted a series of in-depth tests on the device. Reportedly, other independent sources, including Notebookcheck, have also detected similar anomalies, although the documented cases are still limited.
Initially, it was hypothesized that the cause was thermal throttling, or the reduction of performance to contain temperatures. However, Apple’s M5 Max chips are designed to maintain high performance even at temperatures exceeding 100°C, peaking at around 105°C under sustained loads without suffering significant drops. This makes it unlikely that the problem is related to cooling.

Further Details on Testing the MacBook Pro with M5 Max

Additional tests have shown that even enabling High Power mode does not resolve the performance inconsistency, suggesting that the cause is more likely related to defects in specific production batches. In fact, among the six units analyzed by the YouTuber, two experienced similar problems, indicating a limited but real spread of the phenomenon.
The good news is that, in the reported cases, Apple has already replaced the defective units, and the new devices received have shown performance in line with expectations. This suggests that the problem is not systemic, but rather confined to a small percentage of products.
Hypothetically estimating, if Apple had distributed one million units with M5 Max chips in a quarter, even a defect rate of 1% would mean about 10,000 problematic devices. Despite this, the relatively low number of public reports indicates that the company's quality controls remain generally very high.