Since a few days the service suffers from technical site issues and slowness.
There is currently an announcement published by LinkedIn:
We’re sorry, but we’ve identified some site issues that may limit the functionality of certain features or prevent you from accessing your account. We want to get this resolved as quickly as possible, so we have a whole team of experts working to address the problem right now.
At this time, there’s no need to contact LinkedIn Customer Service. Thank you for your patience and please try us again later.