saying 3rd gen i5 is meaningless, especially when it's a laptop. Because some of the laptop grade CPU are crap, whereas higher end CPU can still be quite respectable. And there are manufactures who put desktop grade CPUs into laptops, so the range of power is HUGE.

Unfortunately, 3rd gen is so outdated that they are classified as legacy, so they don't even have their own chart anymore on the intel website. But 4th gen i5 on the low end have dual core 1.3 GHz w/ turbo to 2.6Ghz and another dual core 1.5GHz base that only turbo to 1.9 GHz. Whereas the high end is 3.5GHz that turbo to 3.9 GHz quad cores that is respectable even today.

So for all we know, it could be just that your CPU is worthless. So to make a meaningful complain, you need the exact model of your CPU.

LoL is more optimized than you might think, especially on lower settings. In fact, since most of the actual calculation are server side, there is far more load on your GPU than your CPU. So using that as a benchmark for CPU isn't very meaningful.

You'd have to play some RPG or RTS to measure CPU, especially the single player ones where everything is calculated on your machine.

That said, my 3+ year laptop w/ 5500U can handle at least 3 perfectly w/ no notable lag unless all are in combat and on screen at same time, in which case there might be minor lag. So I reckon 3-4 is about my limit on that. And my desktop would be meaningless for the discussion.