What you are subscribed to is the ISP's 'optimum' speed. All factors being in your favor, that is what you 'could' get.
But factors interfere, and we rarely get what we paid for. In some nations, (here in the UK for example), rows and arguments are brewing between the ISP's and the regulators about this lack of transparency, but in my view progress will be slow.
Traffic. If you log on at a time when the rest of your neighborhood is also logged on, then your available bandwidth will reduce because it is being shared by others.
Maintenance. The ISP is always working on something or other, and that can, at times, affect bandwidth.
Shared network? If you are on a home network, or some other shared network, then other users of the ISP connection will be using your bandwidth.
Also you need to be clear about what you signed up for and what you are currently getting. 730 KB/s may be good. If it was 730 Kb/s that will be 8 times, (or 10 times depending who you talk to), slower than 730 KB/s. The link below may help explain that in more detail;
At the end of the day a call to your ISP might be useful, especially if you still feel that you are being short-changed.
If I pay for 10 mbps download, then when I download something (like software), it only shows speeds of about 730 KB/S. Why are those speeds so much slower than what I pay for?