JodyWood--You could use (the link to) the speed test on the page to which SuperSparks has referred you to determine if your actual connection speed is low or if the problem is elsewhere
http://www.dslreports.com/stest
In any event, it does not hurt to know what your connection speed is for the next suggestion.
Since you have cable and I presume are paying a substantial sum for it, I would call the cable company if SuperSparks suggestions for tweaks do not help. They should send a tech out. Do not accept excuses like service "upgrades", their servers down, other servers down, etc. Do not accept poor service, if, indeed, it is the cable company that is not delivering. You might ask for some reduction in fee.