The computer will be slow overall, not just on the internet or inside of any specific software.
To Resolve: Edit
1. Run CCleaner and TFC. Is there plenty of space available? Open "My Computer" and check.
2. Run a chkdsk on your OS drive. Many times you may have a HDD that is starting to fail.
3. Most of the time this is a common sign of a virus, I recommend you scan with MalwareBytes AntiRootkit and then MalwareBytes Regular (MBAR and MBAM).