I've been trying a couple of ENB presets for Fallout new vegas but all of them makes the game lag so bad ( I get constant 20 Fps )
I have a Radeon HD 7750, can anyone recommend a good enb that isn't to heavy on the fps?

I would recommend Enchanced shaders. I think it got a performance option too. And if you disable/ lover the AA it will help a bit + turn of the dof.

Tried it now I get 30 FPS Minimum, well I guess that's the best I could get with my Graphics card
probably time to upgrade fallout 4 is after all coming out this november.

Overgrowth ENB is my all time favorite enb, i like the feeling it gives me. Try it I dont see any performance change (idk why but no matter what im stuck at 60fps modded or not).

Bleak ENB is my personal choice, not sure what the fps impact is though (i didn't see any).
You should test a handful of ENBs to see which one you like for yourself and saves you performance.

I've been able to run Evolution Ghost ENB on my laptop with an Nvidia 670m gpu. I used the performance options with disabled DOF and AA and get 45-60 fps and it still looks nice. That is with HD texture packs installed as well. I also tried Cobalt and Rust ENBs because I had used them on my desktop but sadly the 670m could not run those as well. You may have better luck with your 7750.

I agree with meowjar overgrowth enb is my favorite, I only suffer minor performance loss.

I use Rudy's ENB, quite good, keeps the atmosphere of the game and it is not FPS heavy :3

I am enjoying 47 enb really makes the lighting feel like a morning sky. Dont forget the weather mod.

give Jay enba shot its quite pretty in my opinion that is.

Definitly Jay's enb, It is the perfect example of perfection in my opinion! I love the blue tent of the wasteland while using the enb!

try the performance version from owergrowth from tru3th or maybye the other enbs from him

overgrowth:

or this enb for vanilia lighting

trompeoil enb:

you can try out
- all stuff from hitman47 (comes with his own weather mod)
- onix enb and rust enb when using rwl

I have been using 47 enb and i am enjoying it so far definatley is an overhaul on the vanilla game but also offers a lot of realism and ermeeeegred the clouds are real good.

Haven't tried it yet but this looks very good in an apocalyptic atmosphere! The author also makes awesome videos, enjoy!