Is there a huge difference Between 3.5 quad 1.5 vs 4.0 quad 1.7?

[gelie]

I tent to have multi apps/ windows open and kind of choking on my 2010 3.2 ghz I3 w/ 8g of memory. Thx

 

[keysofanxiety]

I tent to have multi apps/ windows open and kind of choking on my 2010 3.2 ghz I3 w/ 8g of memory. Thx

Cores & GHz aren't necessarily a benchmark of performance. It's mainly the age/revision of the chipset.

I can advise that the 3.2GHz i3 in your 2010 iMac is a Core i3 (i3-550), which has a CPU benchmark of 2852 (less powerful than a mobile i3-3110M, just to put that in perspective).

The 4GHz i7 in the 2015 Retina iMac is a Core i7 (i7-4790K), which has a CPU benchmark of 11239.

So yeah the i7 would be infinitely more powerful.