Drastic FPS drop in TF2 (and Source games) - Need help

[RPG]

I need some help over here with this.

Yesterday, TF2 was working fine with me, getting its 50-60 fps as usual.
Today, TF2 has been acting up weird on me, starting the round with its normal FPS, and then it reduces to a point were the game is unplayable until I close it. (It takes like.. less than a minute for it to drop)
Not only that, but also my other Steam games suffer this FPS drop (Gmod, Half life 2, Left 4 Dead 2, Poker night at the inventory and Mafia II)

Is other experimating this problem ? or can someone give me a hand here please ?

If it's necessary here is my Pc Specs :
- AMD Athlon II X2 250 Processor 3.0 Ghz
- 2 GB RAM
- 1024 MB GeForce GTX250

[DominationDarre]

Yeah, I was actually having a similar problem with all games that I play in fullscreen. Are you playing TF2 in fullscreen or windowed? Because I seem to only experience sudden FPS drops in games that I play in Fullscreen.

You can still play in windowed mode, but making it still look the same as fullscreen. Change your launch parameters (to do so, go to your Steam library, right-click the game, and choose "Properties". Then select the launch options button, and put in options you'd like) and see what happens.

Personally, what I do with most Valve games is set these as the launch parameters:
-window -noborder -novid
(Actually, -novid has nothing to do with this solution. It just stops the Valve intro from playing, which I like. lol)

Then, go into your in-game video options and set the resolution to whatever your native one is (most of the time it's whatever the largest resolution is) and set it to display in 16:9, if the option is available.

If you do it right it should play in windowed mode, though look the same as fullscreen, and hopefully quit your FPS drops (only if your situation is the same as mine). I'm not sure what fullscreen had to do with it, but that's what fixed my problem.