a reason why my internet is painfully slow tonight?

There are too many variables to take into consideration for your slow internet .

1. Distance you are from Exchange.
2. Condition of equipment, how up to date it is including the Exchange.
3. Age and condition of wiring, joins, corrosion in the system.
4. Line noise. Will affect it badly.
5. How heavily your exchange is subscribed to.
6. How many people are on at any one time.
Any combination of those will drag your speed down.,,

Here a few tips to speed up.
1. Upgrade your Internet Plan
2. Control Bandwidth Usage
3. Free-Up Temporary Directories
4. Optimize your Internet Settings
5. Update Microsoft Silverlight.
I can advise you to download this software,
Download CCleaner 4.15.4725 - FileHippo.com
Good Registry Cleaner which can extremely will improve your computer and Internet performance dramatically! Do all these and Perform speed here ScanmySpeed.com once it will sounds better ...