Performance in iMac System Update

While not a support issue, this is a technical question!

I have a Late 2009 iMac - 2.8GHz quad-core Intel Core i7 processor with 8MB shared L3 cache, upgraded to 12GB of memory. I'm looking at a new iMac, 3.2GHz quad‑core Intel Core i5 (Turbo Boost up to 3.6GHz).

After reading the specs, I'm hesitating - sure I can upgrade memory (up to 32GB) and I'll have other benefits (drive options, display, graphics). But, as these are listed - is there really a performance boost from a 2.8 quad core Core-i7 to a 3.2 quad core Core-i5?

I'd consider a MacBook Pro ... but those use a 2.2 or 2.5 Core i5.

Am I wrong to think I wouldn't gain much with this upgrade? Would it be a significant improvement? I really need to edit photos and occasional 4k footage - and, I'm not getting it done on my Late 2009 iMac - stalling/choking!

Thanks for your advice!

Jeff