Such things do not exist. The speed of a computer, or rather the potential speed of one is determined by the hardware. CPU speed and amount of RAM installed are the two main factors at work.
Same is true for internet connections. If broadband is available in your area, that is the only way to get faster speeds. Don't buy into any of the marketing about 'internet accelerators'.
One last note, while it's very true that software can slow a computer down, the reverse is not true. A fast computer can be slowed down by too much software or running processes. However a slow computer can never be made faster, regardless of what is done to it software wise.
Oh, and welcome to the forum.