So with the recent update that forces Dx9 in MM and makes FPS configs useless, I have a lot less FPS in TF2 than I used to.
I have a 144Hz monitor and already dropped the refresh rate to 120Hz so my fps will dip below it less often.
But it still goes below 120 fps quite often and whenever that happens it becomes impossible to aim.
I already did everything that is still possible to increase your FPS after the update, but I still can't get a real solid 120+ FPS.
I kinda paid too much money for my 144Hz monitor to only run it at 100Hz or less, so now I'm thinking about upgrading my PC to get more FPS.
Question is: what should I upgrade and what would be the most cost-efficient way to make my PC faster?
Here's my current setup:

CPU: i5 3570K @ 4.0GHz
MB: Azrock Z77 PRO4-M
GPU: Nvidia GTX750Ti
8GB RAM
SSD

So from what I hear, TF2 mainly depends on CPU power.
But since my current CPU isn't really all that bad, is there a CPU that would give me a significant performance boost, but doesn't cost a fortune and if at all possible fits on my current MB?
8GB RAM shouldn't be a problem at all, right?
Not sure if my GPU limits my FPS at all? Probably my max FPS, but that's not the issue.

So do you think upgrading my PC would be worth it or not?
Not just in terms of TF2 performance, but also looking at other games that I might want to run in the future like OW for example ;)
Or should I wait untill my PC is more out-dated and I can get a bigger performance boost by upgrading?
Not really up-to-date on current hardware and how fast it is compared to my stuff and how much it costs.