I have just replaced a i5 4460 (8GB RAM DDR3, SSD) with an i3 8100 (8GB RAM DDR4, everything else is the same, except the motherboard, both are in the $100 range).
If I look at tests, the i3 should be about 10% faster than the i5 (the reason for change is that I gave the old i5 to my son since...