Actually there may be a whole bunch of reasons.
Usually I'd tell you how to configure your Firewall and Internet access corectly, but in the last days Mojang prepared everything for 1.7.6 and actually updated the Version.
So it would be very likely for everybody to notice these lags.
But actually you seem to be different. Watch your last line:
(CertificateNotYetValidException:NotBefore:Tue Apr 08 20:47:05 CST 2014)
As you posted this question just an hour ago, and minecraft reports you for sending the wrong time, i guess your time and date is terribly wrong.
This may have two different reasons:
- One of the users at the PC are cheating on any game and tried to turn the time backwards
-> Just set the time to the current time. Thats all. Click here ;)
- Your PC is set to approximately the date 01.01.1970 -> This is most probaly caused by an empty motherboard-Battery. Sure youmay set your date to today and now, but as soon as your restart yur PC it will be gone again. In this case you have got to buy a new battery and get it replaced in your PC. I don't now how old you are or how much experience you've got with electronics, but an open PC may be dangerous. Just open it, if you now what you're doing. Whatever happens, it shall not be my fault.
This would be a link how such a battery may look like: