Very, very few games have proper multi-core support. So then it comes down to single core speeds.
Could have a look at older i5s the problem is that unless you buy second hand, parts have a tendency to barely go down in price, even up a little at the end due to limited stock and then just disappear.
And the old MB/DDR3 ram is about the same price atm so that doesn't really make a difference.
Edit:
here's a 6100 review including avg FPS compared to other current intel CPUsNotes:
-They compare 2 different memory speeds, the one I currently put in the cart is in-between those at 2400
-They attempted to remove the GPU bottleneck by putting something silly in there so don't expect this kind of performance with this build
Anyway, it should mean that the CPU is easily going to be bottlenecked by the 750 ti
Edit #2: actually just checked and the MB doesn't seem to support RAM that's that fast, so that would drop the FPS by a bit and might need to search for some different ram.
Either way, need some food now and may I suggest doing what Kiwi proposed in the other thread and go to sth like r/buildapc to see what they have to say about a budget build.
Quite confident about the CPU being good, it's just that RAM/motherboard combo that's hard to figure out without some serious digging. People on those kind of boards usually have some sort of go-to budget build. (maybe a few different ones depending on whether or not someone wants intel/amd)