Intel Core 5 120U performance debut: Lenovo IdeaPad Slim 3i 15IRU9 laptop review

Note: We have recently updated our rating system and the results of version 8 are not comparable with the results of version 7. More information is available here .

There are a few visual differences between the 2024 and 2023 models. Firstly, the speaker grilles on the bottom cover of the 2023 model have been moved above the top row of keyboard keys adjacent to the Power button. Secondly, the ventilation grilles on the bottom panel have been redesigned with diagonal holes. And lastly, the perimeter around the keyboard is slightly different and more visually defined. Otherwise, the chassis is largely identical year-over-year as the changes are mostly superficial without improving the original quality or rigidity of the build.

Since the chassis is predominantly plastic, the base and lid would flex noticeably more than on a predominantly metal Yoga Pro or ThinkBook. Hinge rigidity is also just average as the lid would teeter for a while when adjusting angles or when using the touchscreen. These attributes are common on budget models where a luxurious experience isn't priority.

Port options remain the same which isn't a bad thing as they are still competitive against others in this price range. Keep in mind, however, that 4K monitors are only supported up to 30 Hz via the HDMI 1.4 port and so we recommend using USB-C when possible.

While some configurations may include a 2 MP webcam, our unit comes with an older 1 MP sensor only. A physical privacy shutter comes standard while IR is not an option.

The packaging is mostly cardboard albeit with polyethylene foam protection and wrapping made of 90 percent ocean-bound plastic.

There are no extras in the retail box other than the AC adapter and paperwork. The usual one-year limited warranty applies if purchased in the US.

Key feedback is on the spongier side especially for the Enter and Space keys which are normally louder and firmer on other laptops. The typing experience is somewhat unsatisfying as a result even when compared to competing models like the Asus VivoBook S15 or Dell Inspiron 15. The softer feedback here is quite noticeable after having just reviewed the Framework Laptop 13.5 and its firmer keyboard keys.

Note that the keyboard backlight is optional and so some configurations may lack the feature.

We set Windows and Lenovo Vantage to Performance mode prior to running the benchmarks below. Owners should become familiar with the Vantage software as it is the control hub for Lenovo-specific settings, updates, and warranty claims.

The Core 5 120U is essentially a rebranded Core i5-1335U as they share the same number of cores and threads, cache sizes, TDP, integrated GPU, and underlying Raptor Lake architecture. Clock rate targets are slightly different, but those are always at the mercy of the manufacturer cooling solution rather than what Intel writes on its specifications. Case and point, the Core i5-1335U in the Samsung Galaxy Book3 15 is consistently faster than the Core 5 120U in our Lenovo in all multi-thread benchmarks since our Core 5 120U would throttle more readily by as much as 22 percent after just one run of CineBench R15 xT.

The strength of the Core 5 120U lies in its single-thread performance where the CPU outperforms pretty much any laptop in this price and size category. Keep in mind that there is no AI acceleration; you'll have to upgrade to the IdeaPad Pro series with Meteor Lake CPUs for such a feature.