not gonna lie, that's not awful with that rig. Dunno how much more you can squeeze out without an upgrade.

15 more fps is good for me, i cant aim with this.

What resolution are you running at? That might be your only option left before an upgrade is absolutely necessary.

Its weird, when i see team mates spamming rockets = no fps drops. When i see enemy shooting = huge fps drop.

800x600, what should i upgrade? CPU, GPU, RAM?

If you want to upgrade something it would be cpu, which means you have to switch your motherboard and ram also for new.
As for now running nohats mod will help you get some more fps

I have the nohats mod, it doesnt help.

Suggestions (some may be obvious):

Computer:
- make sure that nothing is blocking your vents, proper ventilation prevents overheating
- clean out your vents (they might be dusty etc.)

Windows:
- check your power settings, you dont wanna have those in energy-save mode
- run ccleaner every once in a while
- same goes for defragging your pc from time to time
- either optimise windows for high performance (computer>properties/advanced settings/performance) or disable desktop composition when launching tf2 (hl2.exe>properties>compatibility)
- disable windows aero

TF2:
- Razer Game Booster helps to "mute" unneccessary processes while gaming
- process lasso is often recommended, but I'm to dumb for that
- set "-high" in launch options (gives priority, I believe)
- if you aren't already doing it (I think it's required for maxframes), run tf2 with dx8
- updates let your fps go down the drain, I normally do a complete reinstall (dont forget to save your hud, cfg, maps and demos) after every update, some people say deleting the tf folder works, too
- some say that disabling steam community in-game helps with fps, some say it doesn't but you can just try for yourself

That's what I can think of right now, if something else comes to mind I'll update this post.
Hope it helps :)

Experiment with all of the frame improvement configs: dx8 high frames, dx8 max frames, dx9 high frames, etc. Different ones perform differently on different setups, so the best way to see which works best is by testing each of them.

There are reduced particles you can use that remove projectile trails, most smoke and explosions, and significantly reduce the amount of visuals going on. Though this won't work in matches with sv_pure, it should give you a noticeable frame boost in all other environments.

No-hats mod is also an essential for frame boosting, and isn't effected by sv_pure.

Also /experiment/ with different resolutions, not everyone's rig will handle things the same. For instance, I get the best frames @ 1280 x 720, compared to my native resolution (1440 x 900) and even lower resolutions (640 x 360). See what works best for you.

Keeping steam's use of your resources down to a minimum is important too, being this is the only other program you /have/ to have running while playing. Disabling notifications has removed a lot of frame stutters and freezes when they popup for me, as well as the in-game steam community.

Understand the rhythm of your PC, and when it performs best. For instance, I've gotten in the habit of restarting my machine, waiting 10 minutes to launch steam, watching my cpu temperature and usually turning on some additional fans in my room to lower the ambient temp, launching tf2 once I'm at my cpu's comfortable idle temperature, then grabbing an icepack and applying it about 1 minute into the program running. It took me a while to determine one of my main issues was overheating, killing my performance. Especially for those living in scorching, summery climate, it can be very difficult to keep the temperature of your room down to a level that doesn't also give your rig a heart attack. Watch your cpu's temp in relation to your pc, I feel insufficient cooling is a frequent issue, especially for laptop users.

If you do a lot of tweaking and spend time to see what combination of changes works best, you should definitely be able to get 60 fps, atleast /sometimes/. 35-50 isn't a bad starting point. Best of luck.

After that you should probably sacrifice a newborn lamb to the sun gods and maybe pray abit. Only if there is a full moon that night though.

On second thought maybe you should clean your shit if your worried about heat that much. That includes applying new thermal compound. If that still isn't working for you your going to have to spend a big $30 and get a better heatsink and/or a laptop cooling pad.

To the OP, to be honest your computer is shit, and you should be happy with the framerate your getting from it. Sure you can spend hours and gimp your game to the max to try to get 5 more fps, but you will never be happy with the performance you will get from your POS pc. Any actual tangible increases now come from spending a little(and by that I seriously mean alittle) money and getting hardware that has been made in the past 5 years. Yes, it is a 7? year old game, no, I don't give a shit if you think you deserve more fps because of that. Buy a $40 used graphics card from ebay, it will help immensely. I had a 9800gt(an old ass gfx card that you can buy for $40 now) and it was getting hundreds of fps at 1080p with the max frames cfg and a good processor. Your cpu is also limiting but the gfx is worse that it atm. If your actually interested in not having a shitwagon for a pc and want to upgrade, I can help you find useful and affordable parts.