I doubt you would see a massive improvement.
But, you could try.
A i7-4790K goes used for about $200 on ebay.
A used i5-4460 sells for around $100.
To get some sort of an idea how much cpu core speed impacts your games, you could try a back handed experiment.
In windows power management, limit your cpu to 90%.
If this impacts your performance, it will give you an idea of how important 10% cpu performance is.
With a I7, you also get 4 more threads.
This may or may not be important to your games.
I suppose, you could also conduct the same type of aback handed experiment by removing one of your 4 threads.
You do this in the windows msconfig boot advanced options option.
You will need to reboot for the change to take effect. Set the number of threads to less than you have.
This will tell you how sensitive your games are to the benefits of many threads.
If you see little difference, your game does not need all the threads you have.