Try using Comanglia's fps config, chris' one is pretty outdated afaik.
http://www.teamfortress.tv/25328/comanglia-s-config-fps-guide

I'll try using Comanglia's, but I'm surprised that something that has been doing the job for a good amount of time just suddenly stopped working without a reason..

Windows 8 is really terrible to game on, consider getting windows 10 if anything.
If Comanglia's config doesn't work try reinstalling TF2 or refreshing your OS (should be able to do that without losing much data).
If that doesn't work, try looking at your task manager to see which processes are running. If you are using any software in the background while playing, an update to the software might have caused framerate issues in TF2. Try disabling the programs one by one to see which one is possibly causing an issue.
If that doesn't work, then there is probably a hardware issue which I can't help you fix.

Really how so ?

Get Dxtroy and cap your framerate to about 100 and try that if anything
I do a solid 33 fps even in cluttered situations with a laptop that is much more terrible than yours

My bad. I had windows 8 when it first came out and it was horrid for gaming at the time. Constant performance drops and lower performance than Windows 7 across the board, with lacking support for certain games. Looks like Microsoft has done their job and updated the OS to an acceptable standard performance wise.

Windows 8 has better performance than windows 10 and windows 7, although it is a bit weird to get used to. The main problem I have with windows 10 is that every update breaks something, and corrupts the os

How can a windows 10 update corrupt the entire OS??? What are you even talking about

hello if they update it and it messes with the os then everything gets messed up, and i have to reinstall it

the game has updated a lot in five years, even if it doesn't feel like it. commands that were relevant or behaved differently in chris' time no longer function the same way, perform the same action, or just totally break everything because of regressions.

windows 10 has been pretty notorious for pushing updates that completely break the system depending on the prior system configuration. microsoft has been really bad about bugtesting their shit before forcing it on every user

I have never heard of this happening until now, and it's never happened to me and I've been using Windows 10 since it came out...

Having managed around 300 or so Windows 10 installs through work, it's possible you've never run into it, but it sure as hell happens. Mainly with machines that were upgraded - I don't think I've ever seen it happen on a Windows 10 install that started as Win10.

Bumping this thread since its still an annoying issue: I noticed my fps are actually really unstable; the number goes up to ~250 down to ~120 all the time (I would estimate the frequency to 2-3 drops/ups a second). I've ran some benchmarks to see if there was a discrepancy of some sort and here are the results:

Comanglia's (Old cfg that was in my cfg folder)
2639 frames 18.492 seconds 142.71 fps ( 7.01 ms/f) 10.056 fps variability
Chris
2639 frames 17.403 seconds 151.64 fps ( 6.59 ms/f) 11.050 fps variability
Latest Comanglia's
2639 frames 16.824 seconds 156.86 fps ( 6.37 ms/f) 10.589 fps variability

What surprises me the most is the variabilities, it isn't pretty high despite the issue I'm having.. I've also ran a test with only one screen turned on and it didn't change anything. Any suggestions are welcome!

is it happening with other games (csgo)?

check temperatures

make sure there are NO background programs running (antivirus/ntb utilities etc.)
try rolling back/reinstalling drivers (especially graphical)
reinstall windows

Ran some test on CS:GO, same issue.

I installed speedfan, and its most likely a temp issue as the program displays a fire emoticon nearby my Cores and my GPU. What worries me is I cleaned the dust from my laptop's ventilation not so long ago..

No background programs, double checked. I made an update of my graphic card drivers a few weeks ago, that might be it..

NUMBERS, we need NUMBERS!

http://imgur.com/a/jAPiB
Can provide more data if needed

The GPU should not be at 100°C. As in never. It might die.

The CPU is almost definitely throttling in TF2.

Is there a way to fix those issues? My computer being a laptop, its hard for me to clean it "in-depths", as I have little to no knowledge in hardware. I'll open it again tomorrow and see what's inside the box I guess..

Depending on the specific model you might be able to replace the thermal paste, which might be the issue.
Most likely there's not much you can do yourself without the right tools and experience though.
Not sure if you're willing to pay money to have it fixed.

Ok, I'll try to clean the fans one more time, in a glimmer of hope it causes the overheating, otherwise I'll consider spending money either buying a new computer or fixing my laptop.. Thanks a lot for all the clarifications !