2000+ watts on a 15 amp breaker is overload, for certain. Depending you your type of breakers, they should have been tripping and if your wiring is the old fabric coated Romex type, then I would be VERY nervous about it.. To run 5000+ watts, do what everyone is saying and hire the right electrician. Depending on your location, either get a 420 friendly electrician or, if you're in a 420 friendly area, make sure you use a trusted source electrician or you have a good reason why you need that kind of wattage. Side Note: I truly do keep reef tanks and grow coral...these need a lot of Metal Halide and T5 power and it makes a perfect "reason" for having that type of power if you're asked.
Bottom line: get a couple of trusted quotes and spend a couple grand so you can sleep well at night. Hindsight is 20/20 and if you're running 5k watts, the extra couple grand will be a long gone, rear view afterthought very shortly. A house fire will ruin your life and, possibly kill someone.....
How much amperage do you currently have directed to your residence?