Comcast Cable

Remember that most speed test on the internet are from ISP's or ISP owned companies.  (example: Speakeasy.net)  

Also, You have to remember that there are alot of factors that can cause readings to be different from what you expect.

1) Server location: If the server you are running the speedtest is in Japan or something, then sure, it is going to take longer to get here.

2) Server Load: If the server you are testing from is overloaded, that can cause slower results.

3) Router traffic: Each hop between you and the testing server is a router.  If that particular router/hop is under heavy traffic that could slow response times.

These along with many other variables can cause slow your problems.  Comcast or any other ISP can only control their network and not every variable needed.

Good luck.

BTW, Have you tried Speakeasy.net?  I have found it to be among the most accurate.  Make sure you choose the server closest to you.

First, make sure you're properly configured - your network card needs to be either Autonegotiate or HALF duplex.  Auto is better because then you probably get FULL duplex.  However, if you insist on setting it manually, it must be set to HALF if you connect to a device (router or modem) which is Autonegotiate.

Next you might try changing ports or patch cables.  You could have a physical problem pop up on your side which is now causing you problems.

Next, there might be a problem with the physical cabling or modem at your new location.  Is it the same modem or a new modem?  If new, it might have a problem - you might try getting it changed out.  Then the cable which runs through your wall up/down to the Cable Company's location might have a physical problem which is causing errors which equal lower throughput - might be kinked, nicked, crushed.  It might be running parallel to High Voltage and picking up noise which is causing errors which gives you less throughput.  It might just be terminated bad.

If they come out, they need to put a certification tester at the wall where your cable modem is and test the interior cable back to the cable head end - or whatever its called.  

Speaking of that - do you have multiple cable connections in your new place - you might try moving the cable modem and see if quality improves.

HTH

Try the tweak test stuff at BroadBandReports.com:

http://www.broadbandreports.com/tweaks

It is very rare that you would get so consitant speeds all the time as the Internet is a VERY changing place. The site the tech is going to is one on the cable company server, this is the only speed that they can guarantee as it is on their own network, once on the Internet - you are at the mercy of whatever. I have access to a 50M fiber backbone connection and I had a download that topped out at a whopping 18K today. I have had others that have been EXTREMELY fast. Most are pretty good. Each speed test site you go to will usually give you a different reading as they are in different locations. The time of day is a factor. If you have done any updates on you computer, it may read things differently as far as these tests go. If your browser was caching the data - it will give you erroneos speeds. I have notice on some speed test sites that any Mozilla browser will read half of the speed that IE reads - this will throw you off also. It is also possible that the cable company has a server that is having issues getting from their network to the Internet. The only way to 'convince them' of this is to get a program like "Ping Plotter" to track a site over a time period and record the results to see if one device is causing an issue and then you have some evidence to present to the cable company. Hope this helps! ;)

I still think this one:  "If they come out, they need to put a certification tester at the wall where your cable modem is and test the interior cable back to the cable head end - or whatever its called.  "

Possibly a bad/flakey termination.

Also, ideally, any unused Coax termination should have a terminator on it.
http://av-outlet.com/media/DCF59T.jpg

How many cable outlets in your new place? Are there more outlets than old place? From what you describe there may be a signal issue involved i.e. if you have more outlets now you may not be getting a good enough signal. This is what you need to try. Find where the main splitter is in your place - utility room, electrical closet, basement, etc. Find which line feeds to where your modem is, have a TV hooked up to the outlet and turn up the volume until you can hear it where the splitter is and remove one cable at a time until you hear the TV go static. Now the tricky part (lol) purchase a good quality 1 GHz rated CATV 2 way splitter (make sure NOT to get one for a satelite - wrong frequencies) and a small RG6 cable jumper. Take the cable that you found that goes to where your modem is and connect it to one of the "out" ports of the 2 way splitter. Remove the input from the current splitter and connect it to the 2 way splitter. Connect the short jumper from the other "out" of the 2 way splitter and connect this to the input of the current splitter. Some other thing to check is to make sure that there are no "screw on" type fittings (or crimped on) at the end of the cables and that there is no bare braid coming out of the fittings. Either of these can cause a problem. You may also want to look behind the wall plates to check these fittings also. Make sure that all the fittings are tight - actually use a 7/16" wrench ( 30 lbs. is the spec for tightness). All of the above the cable company should have done when they installed the modem or at least checked when they did the service call. If you do find poor fittings or braid showing and don't have access to professional cable tools - call you cable company again to let them know that the previous technician fails to do his job properly and change the fittings out. Most of the 'condo' type housing the electricians will install the fittings and though they do work fo TV (most of the time) they are not very good for broadband services.