Did I Waste Extra Money I Had On i7 8th gen Buy Instead Of i5 8th gen Version ??

ahh after almost one year of using dell Inspiron 15 7572 (i7 8th gen)

I think if I would've bought the i5 - 8th gen version instead of i7 - 8th gen, I would have saved the extra money and the performance would be still the same

AS BEING with specs: i7 - 8th gen and MX150 4GB GDDR5, 8GB RAM 

the games lags a lot alot' actually! - when plugged in or without plugged in (ik power options I've set to max performance still still!? and also runs opposite as with plugged it lags even more, when unplugged run a little smooth atleast) 

i think if I would've purchased the i5 - 8th gen version of the same laptop, it would've been then same and at least would have saved my extra money spent their