The Core i5-1235U had a terrible launch until the Lenovo IdeaPad Flex i5 14 saved it

When the 12th gen Core i5-1235U CPU launched earlier this year, the Gateway Ultra Slim 14 was our first review model to sport the Alder Lake processor. We weren't sure what to expect when it came to performance, but results were disappointing to say the least. Nonetheless, we reserved judgment on the processor as no one laptop is ever representative of any CPU.

The second Core i5-1235U laptop to come in a few weeks later was the Vaio FE14 and, unfortunately, results were similar to what we observed on the Gateway. Overall performance was not any better than the older and cheaper Core i5-1135G7 that the Core i5-1235U was supposed to replace. Our hopes weren't very high for the 12th gen Core i5 processor at this point.

Luckily for users still interested in the Core i5-1235U, our third laptop to come in with the CPU managed to perform significantly faster than expected blowing both the Vaio and Gateway out of the water. As shown by our results below, the Lenovo IdeaPad Flex 5i 14 is 40 to 75 percent faster in multi-threaded applications than either of the two other laptop options. The improvement is so large that the Lenovo is able to outperform most Core i7-1165G7 laptops while being just a few percentage point shy from the Core i7-1255U.

Looking more closely at the Vaio, Gateway, and Lenovo laptops shows why the Lenovo model is so much faster even though they all carry the same Core i5-1235U processor. The CPUs in the Gateway and Vaio stabilize at only 15 W when under stressful loads while the the CPU in the Lenovo would stabilize at 26 W. The Lenovo model draws more power in order to provide faster clock rates and performance.

The performance discrepancies between these laptops present a problem to consumers because it is nearly impossible to know what TDP ranges some laptop models are targeting without deeper research. A user who purchased the Vaio FE14 or Gateway Ultra Slim 14 for their 12th gen Core i5 CPUs, for example, may find themselves disappointed as neither manufacturer makes it overtly clear about how their CPUs will perform. We can at least safely say that the Lenovo IdeaPad Flex 5i 14 is your best bet thus far when it comes to the Core i5-1235U.