how current is my i7 4770K CPU @ 3.50 GHz w/ 16 gigs of RAM?

I've just done a whole upgrade of my Toshiba 16 gig ram, 2 gig AMD graphics card and an i7 CPU...I think similar to yours - I brought this at the start 2015.
 
I was having some difficulty after the last Windows upgrade with the graphics card, and after I decided to use Sonar's full 64bitfp architecture. Basically I could not do a large mix and master at the same time - 30-50 tracks multiple Wave's and Cake plugs. Whilst the CPU on my Toshiba was fine, the memory and the graphics memory were struggling. So to answer your question, a new CPU if your computer is running fine won't really do much. You'd be better off with a Thunderbolt port, and a new Thunderbolt audio interface...this theoretically would give you the ability to play VST effects like Guitar Rig and have latency that was not discernible. 
 
Where you might find a new CPU useful is if you were doing video editing and rendering, something I do also. My old laptop would take 4 hours to render 5-10 mins of footage. Admittedly, I was using the 2 pass option in Vegas Video, and a variable bit rate of 50,000. The render time of my new laptop is between 40-60 mins. 
 
CPU is no longer, I believe the benchmark to measure an audio computer by. Sure, the best CPU will cut down render times for video processing. And indeed, even though my new laptop is an i7 8th gen, apparently the 9th gen CPU would cut down video rendering times even further.
 
For what it is worth, and this will be very unpopular for those wedded to unwieldy desktops - but a good, not even top of the line P.C gaming laptop these days will suffice for all audio work. This is 64bitfp 96khz - although I would not be able to tell you how many tracks you will get to play. At 64bitfp 48khz - i'm finishing a piece at this sample rate - I'm running 58 tracks, and master buss effects...but this is the upper limit of the machine. I freeze all my individual tracks, so that frees up a lot of resources. I have about 10 aux tracks, and 5 busses running though, with each of these tracks containing a number of CPU/Memory hog Wave's plugs like the J37 tape emulator, Wave's NLS on each track, and a slew of tasty EQ and compression tracks.  
 
The specs of my Acer Nitro laptop are 32 gig of ram, 6 gig of graphics ram, internal SSD drive, and a second spindle drive for storage - I have an SSD drive connected to a USB 3 port for audio. The laptop has a Thunderbolt 3 port, so when I can I will be able to connect an audio interface to this which means the machine is future proof (up to 3 years). Not enough?? How about 4k ips monitor, and I've hooked up a second 4k monitor and both are running at 60hz or 60fps refresh rate. It's a sweet ride :) and all for the glorious price of $2500 Oz, so even affordable for those who would prefer a 'pro' audio rig.   
 
Hopefully this answers your question.
 
Ben      

Thx...lots I dont really understand all in the responses...so thinking; "isn't terribly slow" gives me so more use. As said, not really having issues. Thx again

I WAS running an older Pentium 4 and it was chugging along ok.  But my current system is light years beyond that one.  I can do 35 tracks and 12 virtuals....and no issues.  Lots of plugs too.

Track count is determined by disk-speed.
Disk-streaming polyphony (from sample libraries) is determined by disk-speed.
EFX count is determined by the CPU.  Having faster drives won't help in this regard.