I too have been plagued by varying speeds since upgrading from 768 service, to 1.5 service, about a week ago.The speed always seems to slow down around 9:00pm, and pick back up after midnight, though I admit I am not absolutely certain of that pattern. Peak service is usually between 1.0mbps & 1.5mbps, slow service is usually about 500kpbs.
I have had tech support on the phone (outsourced) twice, and done two tech chats. They always run through the same script, os, router, malware, too close to giant magnets (kidding), yadda yadda. (no disrespect, I know they're just doing their job).
Last night the chat technician asked if she could take control of my computer and "optimize" my settings. I agreed. She went through and deleted all temp files (which I do on a regular basis), reset ie default settings, cleared temp & private data in Firefox, and tried to delete Prefetch data (I was on a limited user acct), and a couple other things I didn't' exactly catch. After she had performed these actions, she tested the speed again on Verizon's speed test page, and speed was back up to 1.0mbps. At that point she declared victory, and promptly skedaddled. Trouble is, by this time it was almost midnight. By midnight, speeds were back up to 1.5mbps. So I can't be certain her "optimization" actions are what actually cured my ills.
So far, my speed has stayed around 1.5, even on an admin user acct which she didn't "optimize". Sorry so long winded, I'm almost done, honest. 
My question is, could anything the technician did, actually have any effect on my DSL speed? I guess time will tell, literally.
