25% faster can be microseconds... it can also be minutes... just depends on the activity. But clock for clock, its 25% faster. The 2500K also leaves some FPS on the table with higher end cards... also in multi-GPU setups. Glass ceiling and all.
An SSD loads the OS, games, and applications faster than a HDD, NVME even faster still (though its benefits don't outweigh the costs). The first thing I would do if I was you is snag a 2.5" SSD...it really is the most tangible upgrade to the 'snappy' feeling of a PC.
As far as the ram... no disrespect to you, just what you were told/discovered (and how much it really matters - or NOT)........... WHATEVS on that. Links...?
So, you don't have any usb sticks for storage you use? Interesting..Sounds like you should have just bought a dell...
I'd like to see the 2600K at 5ghz vs 7700K at say 4.5 air then see how it still holds up. So even if the 7700K at 5,on air let's say few do also.. then yeah it's ahead again. But at what point is that really a gain for the typical user like my case.
You edited after I posted.....................................
I just mentioned the gains... 25% IPC. You want 5Ghz on air, you will have to delid or get a better than average chip (go to silicon lottery and pay a small premium). A 7700K at 4.5GHz is, essentially, stock (most boards boost all cores to that value) and it would still clean up the 2500K. On air, you are likely to be more around 4.8Ghz, give or take 100MHz.