I'm assuming you're on a Windows machine
Hit F8 on startup, it's ok to repeatedly tap it like a madman right when you turn on your computer.
This should trigger a menu with several options, the default is "Start Windows Normally"
Choose "Safe Mode With Networking"
Try posting as normal
If it's normal, then there is something bogging down your machine in normal mode.
If that's the case, hold your Windows Key (that's the one with that wavy Windows logo on it) and press "R", it should bring up the Run window
Type "msconfig"
This should bring up a window with all the programs that run on your computer when it starts. Choose "Selective Startup", then on the "Services" and "Startup" tab, uncheck any programs that you don't want running. THere should be a checkbox for "Hide All Microsoft Services" which will make things easier.
The key point is only disable stuff you know you don't need. Obviously stuff like iTunes you don't need running all the time, as it's likely chosen as a player anyway, and you can just click on it if you want to use it.
Once all that is chosen/unchosen, Apply and reboot. See if that helps
Sorry about the Grade School level Step By Step, but this is an element of my day job.